[When he had turned his shoulder, etc.] Samuel had promised that Saul would be changed, etc., after the third sign; but this change happens before this first sign. Thus divine liberality brings it to pass that the promise is fulfilled even more swiftly than promised (Mendoza).
[God changed for him another heart] Question: Whether Saul is made better here, morally, or with respect to his behavior? or civilly, or more apt to rule citizens? I could accept both. However, Interpreters more commonly refer it to the Royal state. Thus Tostatus, Hugo Cardinalis, Carthusianus, Theodoret, and Procopius. And rightly indeed; although they do not exclude moral virtues, which are required in order to discharge the Royal office rightly (Mendoza). That is to say, God made the heart of Saul, which, while he was a private man, was small, mean, rude, and servile; with him now made King, noble, eminent, great, and royal (Lapide, similarly Sanchez). God placed in him a heart, or a Royal spirit (Vatablus). He made him braver and more prudent than usual; and, lest he should doubt himself destined for the kingdom, God also granted to him a temporary gift of Prophecy, verse 11. A similar thing is found in 1 Samuel 19:20. But that Spirit, fit for administrating the Kingdom, God afterwards removed from him for the punishment of sinners, 1 Samuel 16:14. Compare Psalm 51:11 (Grotius).
[All these signs came on that day] Which was easily able to happen; since the city of Ramah, from which Saul was departing, was not very far from Gibeah, his home, to which he was traveling (Mendoza).
Verse 10: And (1 Sam. 10:5) when they came thither to the hill, behold, (1 Sam. 19:20) a company of prophets met him; and (1 Sam. 10:6) the Spirit of God came upon him, and he prophesied among them.
[And, behold, a troop of Prophets, etc.] He passes over the two prior signs, both because they were not pertaining to public notice, and the certainty of the choice of Saul, but only to the private certification of Saul; and because in the prior signs nothing had happened other than what had been predicted; especially when from what precedes they are manifestly supposed to have happened. But the third sign is mentioned separately; because this pertains to the certification of the others; that the people, seeing him inspired by the divine Spirit, might afterwards easily believe him to have been chosen as King by God (Mendoza).
Behold, a company of prophets, etc.: Then the accomplishment of the two former signs is supposed, and this only of the third is expressed, because this was more eminent and public than the former: the other were only transient acts, which passed in private between two or three persons meeting together, and passing by one another; but this was a more permanent and more notorious sign, done in a more solemn manner, and before many and very considerable witnesses.
[He leapt upon him] It indicates that the gift and time were limited. But the Holy Spirit is said to have descended, and to have remained, upon Christ, John 1:33 (Mendoza).
[And he prophesied] Of this prophecy a twofold cause is assigned in this place. One effective, namely, that leaping upon of the divine Spirit. The other exemplary, namely, the presence of the other prophets prophesying together. The society of good men is most useful for the reformation of manners (Mendoza).
Verse 11: And it came to pass, when all that knew him beforetime saw that, behold, he prophesied among the prophets, then the people said one to another (Heb. a man to his neighbour), What is this that is come unto the son of Kish? (1 Sam. 19:24; Matt. 13:54, 55; John 7:15; Acts 4:13) Is Saul also among the prophets?
[That he was with the prophets] Lingering with them in a familiar manner, a Benjamite among Levites. They were marveling at this first; then that he was prophesying, whom they knew to be unskilled in singing (Mendoza).
[Is Saul also among the prophets?] They functions of singing the divine praises were pertaining to the Levites alone, as it is evident from 1 Chronicles 16; 25 (Mendoza).
What is this that is come unto the son of Kish? what means this strange and prodigious event? Saul; a man never instructed nor exercised in nor inclined to these matters; a man ever thought fitter to look to his father’s asses, than to bear a part in the sacred exercises of the prophets.
Verse 12: And one of the same place (Heb. from thence) answered and said, But (Is. 54:13; John 6:45; 7:16) who is their father? Therefore it became a proverb, Is Saul also among the prophets?
[And one was answering another, saying, וַיַּ֙עַן אִ֥ישׁ מִשָּׁ֛ם] And responded a man from there (Montanus, Pagnine, Jonathan), or one of those (Septuagint). And one responding hence (Munster), or thence (Tigurinus, Vatablus), that is, one that was present (Vatablus), either originating from that place (Junius and Tremellius, Drusius), or thence (Syriac, Arabic), from that people, namely, who knew before this that Saul was not a prophet (Tigurinus Notes). Or perhaps he was one of the number of those prophets (Junius).
One of the same place; Hebrew, one from thence, that is, one of the company there present, or one of the prophets there prophesying.
[And who is their father? (thus Jonathan, Pagnine, Montanus, Munster, Tigurinus, Castalio, Vatablus, Drusius)] Others: who is his father? (Syriac, Arabic, Septuagint). [They take it variously:] 1. Some explain it by Auxesis; that is to say, How was Saul so suddenly made a prophet, indeed, a father and master of prophets? for Saul was preeminent among them in singing (certain interpreters in Lapide). Not only is Saul a prophet, but also the father, that is, the highest, of the the prophets (Castalio). 2. Who is the father of them? that is, of Saul and his servant? That is to say, they do not have this art of music from ignorant, rude, and rustic parents (Tirinus out of Cajetan and Lyra and Hugo). 3. Who is the father of them? that is, of the prophets? The sense is, It is not strange if Saul, born of rustic parents, sings in the chorus of the prophets; since those Prophets also were born of parents no more noble or learned than Saul’s: because, of course, the spirit and faculty of prophesying is not derived from one’s parents, but from another (Menochius, Mendoza, Lapide). Are their fathers Prophets? (Vatablus). 4. It is not strange if Saul prophesies, although he be not a son of a prophet; since the gift of Prophecy is conferred by God, but is not derived from family heritage (Lapide out of Dionysius and Hugo, similarly Sanchez). Who was their father? (Jonathan in Vatablus), that is, who taught them? that is to say, who taught the prophets, and gave to them the spirit of prophecy; He was also able to teach Saul, and to give to him the prophetic spirit (Vatablus). Their Father; that is, their Founder: that is to say, do you think these to be Prophets, because they were instituted by men only; and not rather, because they had the gift of prophecy from heaven? (Junius, Piscator, Malvenda). Father is here teacher and preceptor (Munster, Drusius). Thus the sons of the Prophets are their Disciples (Drusius).
Who is their father? who is the father of all these prophets of whom you speak, and among whom Saul now is one? who is it that instructs and inspires them with this holy art, but God? They have it not from their natural parents, nor from their civil education, but by inspiration from God, who, when he pleaseth, can inspire Saul, or any other man, with the same skill. And therefore wonder not at this matter, but give God the glory of it. Father is here put for teacher, or instructer, as it is used; as Genesis 4:20, 21; Matthew 23:9; 1 Corinthians 4:15. And hence the scholars are called sons of the prophets. It became a proverb, used when any strange, unlikely, or unexpected thing happened.
[Is Saul among the prophets?] From the sudden change in Saul, this expression erupted from those standing by; which was converted into a proverb: it is similar to one of ours, a goose among the swans, a raven among the muses (Lapide). It is a Proverb among those that, although previously obscure, are made illustrious and noteworthy (Vatablus out of Munster). Or concerning one that furnishes anything beyond expectation (Junius, Piscator). Because of a similar event, mention is made of this proverb again in 1 Samuel 19:24. That is to say, Who would have expected this in a military man? But of course Πολλάκι καὶ κηπωρὸς ἀνὴρ μάλα καίριον εἶπε, Even a vegetable-grower often speaks advantageous things. And the Spirit bloweth where He willeth, John 3:8 (Grotius). That is to say, the Lord is able to teach whom He wills, and to give the prophetic spirit (Vatablus).
 Hebrew: וְהָיָ֗ה כְּהַפְנֹת֤וֹ שִׁכְמוֹ֙ לָלֶ֙כֶת֙ מֵעִ֣ם שְׁמוּאֵ֔ל וַיַּהֲפָךְ־ל֥וֹ אֱלֹהִ֖ים לֵ֣ב אַחֵ֑ר וַיָּבֹ֛אוּ כָּל־הָאֹת֥וֹת הָאֵ֖לֶּה בַּיּ֥וֹם הַהֽוּא׃  Hebrew: שִׁכְמוֹ.  Hebrew: וַיַּהֲפָךְ.  Hebrew: וַיָּבֹ֤אוּ שָׁם֙ הַגִּבְעָ֔תָה וְהִנֵּ֥ה חֶֽבֶל־נְבִאִ֖ים לִקְרָאת֑וֹ וַתִּצְלַ֤ח עָלָיו֙ ר֣וּחַ אֱלֹהִ֔ים וַיִּתְנַבֵּ֖א בְּתוֹכָֽם׃  Hebrew: וַיְהִ֗י כָּל־יֽוֹדְעוֹ֙ מֵאִתְּמ֣וֹל שִׁלְשׁ֔וֹם וַיִּרְא֕וּ וְהִנֵּ֥ה עִם־נְבִאִ֖ים נִבָּ֑א וַיֹּ֙אמֶר הָעָ֜ם אִ֣ישׁ אֶל־רֵעֵ֗הוּ מַה־זֶּה֙ הָיָ֣ה לְבֶן־קִ֔ישׁ הֲגַ֥ם שָׁא֖וּל בַּנְּבִיאִֽים׃  Hebrew: אִ֣ישׁ אֶל־רֵעֵ֗הוּ.  Hebrew: מִשָּׁם.  Hebrew: אִ֥ישׁ מִשָּׁ֛ם.  Hebrew: וּמִ֣י אֲבִיהֶ֑ם.