Poole on 1 Samuel 3:21: Jehovah's Self-Revelation to Samuel
(circa 1141 BC) Verse 21: And the LORD appeared again in Shiloh: for the LORD revealed himself to Samuel in Shiloh (1 Sam. 3:1, 4) by the word of the LORD.
[And the Lord added to appear in Shiloh] The Septuagint adds, to him, that is, to Samuel (Lapide, Vatablus). It is a Hebraism: that is to say, He appeared again (Mendoza, Pagnine).
[For He had revealed, etc., כִּי־נִגְלָה וגו״] Since or for the Lord had manifested (revealed [Munster, Tigurinus, similarly the Dutch, English]) Himself to Samuel in Shiloh (Munster, Jonathan): that is to say, because the Lord had begun to appear to Samuel in Shiloh; hence He went on appearing to him in the same place (Lapide, Sanchez). For God is constant; and therefore He constantly advances and pursues the things that He has begun: Wherefore the collation of the one benefit is a reason and stimulus for conferring the other. It is otherwise among men; who, since they are of a parsimonious mind, when they will have given one benefit, deny the other (Lapide, similarly Mendoza). Or, since, is put in the place of, just as; that is to say, Thus the Lord appeared to Samuel a second time, just as He had appeared a little before (Mendoza). Just as He appeared to Him at first in Shiloh, so He appeared to Him in that place a second time (Munster). Others thus: Jehovah was proceeding to appear, etc., after He had revealed Himself; that is, after He had begun to reveal Himself above, verse 7 (Junius, Piscator, Glassius). It is a Synecdoche of Genus, which sort is in Genesis 5:32 (Piscator). For completive verbs are often to be understood inchoatively; like he begat, for he began to beget, Genesis 5:32; 11:26. Thus in 2 Samuel 2:10, when he reigned; that is, when he began to reign (Glassius’ “Sacred Grammar” 233). And כִּי here is taken for when, after; as it is done elsewhere: Thus in 2 Samuel 7:1, כִּי/when the King dwelt, etc., in the place of which in 1 Chronicles 17:1 כַּאֲשֶׁר, when, or after, is found. Thus in Proverbs 23:22, כִּי/ when she is old (Glassius’ “Sacred Grammar” 441). Now, these things appear to have been added in contrast with those things that were said above, verse 1 (Malvenda).
The LORD revealed himself to Samuel: Or, did use to reveal his mind to Samuel.
[According to the word of the Lord, בִּדְבַ֥ר יְהוָֽה׃] In the word, or speech, of the Lord (Montanus, Pagnine, Jonathan, Junius and Tremellius); or by the speech, or word, of the Lord (Piscator, Drusius, Dutch, English). The antecedent in the place of a relative; or a Noun in the place of a pronoun (Vatablus, Drusius, Piscator, Glassius). In the place of, with His word (Vatablus). Or, by His speech (Piscator). Similar expression: the Lord said, Come up unto the Lord, that is, to me. Thou shalt destroy them from under the heavens of the Lord, that is, thy heavens (Drusius). Thus in 1 Samuel 15:22; 2 Chronicles 7:2; Leviticus 14:15, the priest shall take…and shall pour it into the hand of the priest (Glassius’ “Sacred Grammar” 198). But what does this phrase mean? Or, What then is this word? Responses: 1. Christ Jesus: who indeed, in earlier periods, was called the Angel of Jehovah; but thereafter, as He revealed Himself more clearly in the succeeding age, He was called the Word of Jehovah; as in 2 Samuel 7:21; and that distinction, of which the author made use above, verse 1, had regard to this (Junius). 2. Some understand speech, of which above (Drusius). With thy word, that is, making certain hidden things known to him (Vatablus). That is to say, He manifested Himself to him, as He is wont to do with other Prophets; by revealing to him His hidden things (Mendoza out of Sà and Mariana). He revealed Himself to him by dreams and visions; and also by speaking with him; which rarely happened previously (Dutch). Only by the word; with no sensible appearance of a body exhibited (Menochius out of Sanchez). 3. Others understand it of the word that Samuel afterwards had for the Israelites, concerning war, that is, to be undertaken against the Philistines. This is to be seen in Rabbi Kimchi (Drusius). With His word, giving certain things to Samuel to be said to Israel (Vatablus).
By the word of the Lord, that is, by his word, the noun for the pronoun, which is frequent, as Leviticus 14:15, etc.; by his word of command, which he chose to deliver to Israel by his mouth, as it here follows; or by his word of prophecy concerning future events.
 Hebrew: וַיֹּ֥סֶף יְהוָ֖ה לְהֵרָאֹ֣ה בְשִׁלֹ֑ה כִּֽי־נִגְלָ֙ה יְהוָ֧ה אֶל־שְׁמוּאֵ֛ל בְּשִׁל֖וֹ בִּדְבַ֥ר יְהוָֽה׃  2 Samuel 7:1, 2: “And it came to pass, when the king sat in his houseכִּי־יָשַׁ֥ב הַמֶּ֖לֶךְ) בְּבֵית֑וֹ), and the Lord had given him rest round about from all his enemies; that the king said unto Nathan the prophet, See now, I dwell in an house of cedar, but the ark of God dwelleth within curtains.”  1 Chronicles 17:1: “Now it came to pass, as David sat in his houseכַּאֲשֶׁ֛ר יָשַׁ֥ב דָּוִ֖יד) בְּבֵית֑וֹ), that David said to Nathan the prophet, Lo, I dwell in an house of cedars, but the ark of the covenant of the Lord remaineth under curtains.”  Exodus 24:1.  Lamentations 3:66.  Leviticus 14:15: “And the priest shall take some of the log of oil, and pour it into the palm of the left hand of the priest (עַל־כַּ֥ף הַכֹּהֵ֖ן הַשְּׂמָאלִֽית׃)…”  See 1 Corinthians 10:9.