Verse 5: And Samuel said, (Judg. 20:1; 2 Kings 25:23) Gather all Israel to Mizpeh, and I will pray for you unto the LORD.
[And Samuel said] Through messengers, whom he sent through all Israel (Mendoza).
[Unto Mizpeh, הַמִּצְפָּתָה] The ה is in the place of the article; that is to say, unto that Mizpeh, which is famous for that victory in Joshua 11:3 (Vatablus). This is not the Mizpeh of Jephthah, concerning which Judges 11:11, 29, but another in the confines of the tribes of Benjamin and Judah, as Adrichomius thinks. Objection: But Asa is said to have built long afterwards, 1 Kings 15:22. Responses: Either, 1. Asa restored it to the extent that it had been destroyed; or, 2. this was another city of the same name (Mendoza). Question: Why are they congregated at Mizpeh? Responses: 1. Because there, by the help of God, they defeated the kings, Joshua 11 (Vatablus). This place was famous for sacred assemblies of the Israelites. See Joshua 18:26; Judges 20:1 (Malvenda). There the Israelites erected an altar and place of prayer (Rabbis in Martyr, Drusius). 2. Because there from all parts of Israel they were able conveniently to be assembled (Menochius, similarly Sanchez). 3. It was a seat of the kingdom, since in it Samuel was judging (Lapide out of Mendoza). Samuel wanted public idolatry to be wiped out, not only by private abjuration, but also by public abjuration in a public place (Mendoza).
Verse 6: And they gathered together to Mizpeh, (2 Sam. 14:14) and drew water, and poured it out before the LORD, and (Neh. 9:1, 2; Dan. 9:3-5; Joel 2:12) fasted on that day, and said there, (Judg. 10:10; 1 Kings 8:47; Ps. 106:6) We have sinned against the LORD. And Samuel (Ecclus. 46:14) judged the children of Israel in Mizpeh.
To Mizpeh; not that beyond Jordan, of which Judges 11:11, 29; but another in Canaan, where the Israelites used to assemble, Judges 20:1; 1 Samuel 10:17.
[And they drew water, and poured it out in the sight of the Lord (similarly all interpreters)] It is an extraordinary and difficult passage: which expositors have not sufficiently explained (Malvenda). 1. The Rabbis feign that this water was probatory, which sort was that in Numbers 5:12; Exodus 32, that, with it swallowed, the lips of idolaters would cleave to it, and would not be able to part from it (Lapide, Mendoza). But the water is said to have been poured out, not drunk (Martyr). 2. Others take it of tears of repentance. Who follow the Chaldean Paraphrast, who speaks thus, they drew the waters from the well of their heart, and wept them abundantly before the Lord in repentance (Vatablus). The poured out water signifies tears (Grotius). It is a hyperbolic description of great lamentation: that is to say, with their eyes they pourout streams of tears, drawn from the fount of the heart, before the Lord; of which hyperbolic sort of speaking the Psalms are full (Junius). Similar descriptions occur in Psalm 6:7; 119:136; Jeremiah 9:1; Lamentations 3:48, 49 (Glassius’ “Sacred Rhetoric” 472). Albeit an external symbol of this sort is able to agree with this repentance; which is allowed by us, to any it is pleasing thus to understand (Junius). 3. Therefore, others say more agreeably to the letter that an external ceremony intervened in this place, and that water was actually drawn from a well, and poured out before the Lord (Mendoza, thus nearly all interpreters). But what and for what purpose was this ceremony? Responses: 1. Some think it to have been a specific rite of libation, wherein they poured out water to God (certain interpreters in Malvenda, Josephus and Bede in Mendoza). Thus did David in 2 Samuel 23:16. And libations of pure water were formerly sacred to the Gentiles: Homer’s Odyssey 12, Virgil’s Æneid 8, Heliodorus’ Æthiopica 2:5. But we find no rite of the pouring out of pure water in the law; and David’s act was singular (Malvenda). Drink-offerings were made of wine, oil, etc., but not of water. And only the priests were pouring out the libations. But here, all poured out water (Mendoza). 2. This ceremony was employed to confirm the covenant. Now, covenants were wont to be confirmed with various external signs (Mendoza). 3. This drawing and pouring out of water was to the people for a sign of faith of the remission of sins, saying, Let our sins vanish, like this water [poured upon the earth]; blot out our sins (Hebrews in Vatablus). Others understand the waters wherewith they cleansed the filth of the body, so that they might signify that the soul was in like manner to be purged from the stains of sin. Others, which is more likely, understand the waters poured out upon the earth as a sign of the expiation of iniquities, according to that saying in Job 11:16, as waters that pass away thou shalt not remember (Bochart’s A Sacred Catalogue of Animals 1:2:34:352). 4. Others maintain that this was done as a sign of humiliation; that is to say, Before thee we are as water pour out, which is worthless, and is easily poured out, and, having been poured out, is good for nothing (certain interpreters in Mendoza). 5. Or thus they were signifying the affection of the heart, and their desire to adhere to God, which they were pouring out in prayer in the sight of the Lord (Menochius). 6. Or it is a manner of swearing; that is to say, May we thus perish, like water poured out of a vessel, if we violate the covenant with God (Sanchez in Menochius). 7. This was done in detesttion of idolatry, which they were desiring to put away completely; in such a way that no vestige might survive: just as water poured out cleaves not at all to the vessel, otherwise than happens in the case of oil, honey, and other liquids of that sort (Menochius, similarly Sanchez). Water poured out leaves nothing of itself in the pot, neither color, nor smell, nor taste (Cajetan in Mendoza). Often in Sacred Scripture we see that, when anything is exhibited as completely empty, it is signified by water poured out. Thus God is said to pour out His wrath, when He vomits it all out, Deuteronomy 12; Hosea 5:12. Is it strange then, if what is often expressed in a metaphorical word is expressed by a hieroglyphic sign? Therefore, this was a symbol of a truly penitent soul, which suffers nothing of the prior life and manner to remain (Tirinus out of Sanchez). 8. This was an external and visible sign, whereby they were reminded of their impurity, and of removing the uncleanness, whereby they were provoking the judgment of God againt them; whereby they were also professing that they were polluted, and that their cleansing was not in themselves, but was to be sought elsewhere (Calvin). 9. This was a symbol of devout prayer, whereby they poured out their heart, as it were, as in 1 Samuel 1:15 (Piscator). 10. I think that they did nothing here alien to the law. For God in the law had prescribed many sorts of cleansings and baptisms: But in this manner they were confessing themselves to be unclean. To have poured out water was this, to have cleansed themselves according to the precept of the law, so that they might be purified (Martyr). Lustrations of pure water were performed, Virgil’s Æneid 2: …until I shall have washed myself in a flowing stream…. Sacrificial animals were also thoroughly washed with pure water (Malvenda). Moreover, this is said to have been done before the Lord, either, 1. because before the Ark, conveyed there from Kirjath-jearim (Piscator). Or, rather, 2. because those things were done in a sacred assembly: in which, piously and lawfully celebrated, God Himself always presides, according to Matthew 18:20. Wherefore we ought not to neglect sacred assemblies, as in which we are always going to have God present (Martyr).
Drew water, and poured it out; which they did either, 1. Figuratively; they drew tears out of their hearts, and poured out of their eyes as it were rivers of water; such descriptions of penitential sorrow being not unusual. See Psalm 6:7; 119:136; Jeremiah 9:1; Lamentations 3:48, 49. Or rather, 2. Properly, because they are said first to draw it, and then to pour it out. And this agrees well with the state of those times, wherein such rites as this were very customary. Now this course they seem to have used, either, 1. As a mean or instrument of their purification. So they washed themselves in this water, thereby acknowledging their filthiness, and cleansing themselves as the law prescribed. But this seems not probable, 1. Because here is only mention of drawing and pouring forth this water before the Lord, but not of any washing themselves with it. 2. Because this was not a fit time and place to purify themselves in this great and general assembly. Or, 2. As an external sign, whereby they testified and professed both their own great filthiness and need of washing by the grace and Spirit of God, and blood of the covenant, which are oft signified by water, and their sincere desire to pour out their very hearts before the Lord in true repentance, and to cleanse themselves from all filthiness of flesh and spirit. Before the Lord, that is, in the public assembly, where God is in a special manner present, as hath been noted before.
[And they fasted] This fast was either undertaken spontaneously; or, which I prefer, proclaimed by Samuel. Moreover, the fasts of the Jews were strict; whence, being about to speak of strick fasts, Martial, Epigrams 4:4, called them the Fasts of the Sabbatarians. See also Suetonius, “Octavius” 76 (Mendoza).
[And Samuel judged the children of Israel at Mizpeh] It is a matter of some doubt, why this is written here. Responses: 1. Because from this time he undertook hiw office (Serarius, Cajetan in Mendoza). This does not satisfy; for thus the people would have been without a Judge for twenty years between Eli and Samuel; and those twenty years are to be added to the years of the Judges: whence the number of years will be greater than the Scripture relates, 1 Kings 6:1 (Mendoza). I understand this passage in this way: Samuel was previously designated Judge by God; now he is publicly declared Judge by Him. And so he, according to the manner of his office, asserts the liberty of the people. For שָׁפַט, to judge, is not to make rulings, but to vindicate liberty. Samuel was already a Prophet, but now he is made Judge (Martyr). 2. This is commemorated, because he not only gathered the people to God there; but he also he also removed the disagreements of that people, and composed their quarrels, etc. (Mendoza, Lyra, Tostatus). For, although all these things related to that entire period of twenty years, he more carefully watched over this responsibility, especially at that time, in which the whole people were returning to God (Mendoza). There he sit as judge for the penitent people, and corrected the corrupt state of the Republic and Church. See 1 Chronicles 9:22 (Junius, Piscator, Malvenda). Samuel previously ranged through various places, so that he might admonish all of of their forsaken duty, and of their neglected religion: But now he established himself an abiding seat in Mizpeh, where he might sit as judge, and govern public affairs (Sanchez).
[He judged] That is, he broke up quarrels, and the controversies that were among the Israelites (Vatablus). Since the people had already returned unto favor with God, it was most likely that the internal strife and injuries among them were composed. Therefore, he judged; that is, he gave attention that all memory of injuries among the people might be completely removed (Martyrs). Others: he judged; that is, he punished idolaters with death (Hebrews in Lapide).
Samuel judged the children of Israel, that is, governed them, reformed all abuses against God or man, took care that the laws of God should be observed and executed, and wilful transgressors punished.
 Hebrew: וַיֹּ֣אמֶר שְׁמוּאֵ֔ל קִבְצ֥וּ אֶת־כָּל־יִשְׂרָאֵ֖ל הַמִּצְפָּ֑תָה וְאֶתְפַּלֵּ֥ל בַּעַדְכֶ֖ם אֶל־יְהוָֽה׃  Hebrew: וַיִּקָּבְצ֣וּ הַ֠מִּצְפָּתָה וַיִּֽשְׁאֲבוּ־מַ֜יִם וַֽיִּשְׁפְּכ֣וּ׀ לִפְנֵ֣י יְהוָ֗ה וַיָּצ֙וּמוּ֙ בַּיּ֣וֹם הַה֔וּא וַיֹּ֣אמְרוּ שָׁ֔ם חָטָ֖אנוּ לַיהוָ֑ה וַיִּשְׁפֹּ֧ט שְׁמוּאֵ֛ל אֶת־בְּנֵ֥י יִשְׂרָאֵ֖ל בַּמִּצְפָּֽה׃  Ecclesiasticus: “By the law of the Lord he judged the congregation, and the Lord had respect unto Jacob.”  Hebrew: וַיִּֽשְׁאֲבוּ־מַ֜יִם וַֽיִּשְׁפְּכ֣וּ׀ לִפְנֵ֣י יְהוָ֗ה.  Heliodorus of Emesa, Syria, (third century AD) wrote a Greek novel, Æthiopica, which is set completely in Ethiopia.  1 Samuel 1:15: “And Hannah answered and said, No, my lord, I am a woman of a sorrowful spirit: I have drunk neither wine nor strong drink, but have poured out my soul before the Lord (וָאֶשְׁפֹּ֥ךְ אֶת־נַפְשִׁ֖י לִפְנֵ֥י יְהוָֽה׃).”  Hebrews 9:10.