Poole on 1 Samuel 17:12-15: David's Family Circumstances
Verse 12: Now David was (1 Sam. 17:58; Ruth 4:22; 1 Sam. 16:1, 18) the son of that (Gen. 35:19) Ephrathite of Beth-lehem-judah, whose name was Jesse; and he had (1 Sam. 16:10, 11; see 1 Chron. 2:13-15) eight sons: and the man went among men for an old man in the days of Saul.
[Now, David was the son of an Ephrathite man, who was mentioned above (thus Vatablus), וְדָוִד֩ בֶּן־אִ֙ישׁ אֶפְרָתִ֜י הַזֶּ֗ה וגו״] And David was a son of an Ephrathite man; he was of Beth-lehem of Judah (Septuagint, Hebrew Manuscripts). But that David was the son of an Ephrathite man (Pagnine). Now, David was that son of the Ephrathite (Junius and Tremellius, similarly Malvenda). That one, namely, of whom mention was made above in 1 Samuel 16:19 (Junius, Piscator, Malvenda). And by this pronoun is confirmed that πρωθύστερον, the last set first, which was treated in verse 1 (Piscator). Others: David was the son of a certain Ephrathite (Syriac, Arabic, Munster, Tigurinus, Strigelius, Glassius, Osiander). The pronoun is demonstrative, זֶה הוּא, that one, he, etc., whenever a certain one appears to be taken indefinitely. Thus here, and in verse 34, there came a lion, and a bear, and took זֶה/zeh/that (that is, a certain one) from the flock (although there the Chaldean, the Frankfurt edition, and two Manuscripts read שֶׂה/seh/lamb, as Junius testifies): thus in 1 Kings 19:5, and behold, זֶה/that (that is, a certain) angel touching him, etc. (Glassius’ “Grammar” 187).
The son of that Ephrathite, that is, of the man of Ephratah, or Beth-lehem, Genesis 35:19.
[Who had eight sons] Perhaps with a grandson included (now, grandsons are called sons), Jonadab, the son of Shimeah, of whom 2 Samuel 13:3 (Junius, Piscator).
He had eight sons: see on 1 Samuel 16:10.
[And in the days of Saul he was an old man, and of great age among men, וְהָאִישׁ֙ בִּימֵ֣י שָׁא֔וּל זָקֵ֖ן בָּ֥א בַאֲנָשִֽׁים׃] Now, he was in the days of Saul an old man (Pagnine, similarly Montanus, Jonathan, Syriac, Junius and Tremellius, etc.), coming (he was coming [Tigurinus]) among men (Septuagint, Pagnine, Montanus, Tigurinus), understanding, of old age; thus in Genesis 24:1, he came into days, namely, of old age, as the Hebrews explain; that is to say, reckoned among the aged and feeble (Vatablus). Elderly among old men (Junius and Tremellius); he had come as an old man among men, that is, he had grown very old compared with the rest of the men. For the superlative degree is sometimes presented by an adjective governing an ablative with the preposition ב/in. Thus in Psalm 94:8, בֹּעֲרִ֣ים בָּעָ֑ם, brutes among the people, that is, the most brutish of the peoples; in Proverbs 30:30, גִּבּ֣וֹר בַּבְּהֵמָ֑ה, strong among the beasts, that is, strongest of the beasts; in Song of Solomon 1:8, הַיָּפָ֖ה בַּנָּשִׁ֑ים, beautiful among women, that is, most beautiful of women; in Jeremiah 49:15, קָטֹ֛ן נְתַתִּ֖יךָ בַּגּוֹיִ֑ם, small among the nations will I make thee, בָּז֖וּי בָּאָדָֽם׃, despised among men, that is, the smallest of the nations, the most despised of men (Glassius’ “Grammar” 57). He was of advanced age (Arabic, Castalio), he was reckoned among the chosen (Jonathan), that is, the mighty and renowned (Vatablus). That is to say, he was old in years, young in strength (Mariana, Malvenda). Others contrariwise: among the sick, and weak because of age (Malvenda, Kimchi in Buxtorf). Entering among the infirm. This opinion appears the simplest. For אֱנוֹשׁ/man properly signifies this (Buxtorf’s Vindication 2:13:996). He went among men consumed with agae, so that he was not able to come to battle (Munster). An old man and of great age among men; and so he had already obtained exemption from military service (Osiander). He was not only old, but of an especially advanced age even among old men. In the place of בַאֲנָשִׁים, among men, some books have בְשָׁנִים, in years, which is not unsuitable in this place (Grotius, similarly Castalio). Thus the Septuagint read it. For in the Complutensian edition it has ἐν ἔτεσι, in years; he was advanced in years (Syriac, similarly Strigelius). This reading is better in every way, than בַאֲנָשִׁים, among men, with the expression obscure and strange (Cappel’s Sacred Criticism). [It is viewed differently by Buxtorf:] That expression, בָּ֥א בַאֲנָשִֽׁים׃, he went among men, occurs nowhere else (Buxtorf’s Vindication 2:13:996). Others translate it, he came with men; so that wherever he might proceed, they would surround him for the sake of honor (certain interpreters in Munster, the Talmud in Buxtorf). Thus Abarbanel explain its: he was one, and hence he himself would no longer proceed to battle; but in his place he sent אֲנָשִׁים/men (and thus the sense of the words, בָּ֥א בַאֲנָשִֽׁים׃, will be, he went, he proceeded to battle, although not in his own person, but through men sent by him) (Buxtorf’s Vindication 2:13:996).
Verse 13: And the three eldest sons of Jesse went and followed Saul to the battle: and the (1 Sam. 16:6, 8, ; 1 Chron. 2:13) names of his three sons that went to the battle were Eliab the firstborn, and next unto him Abinadab, and the third Shammah.
Verse 14: And David was the youngest: and the three eldest followed Saul.
Verse 15: But David went and returned from Saul (1 Sam. 16:19) to feed his father’s sheep at Beth-lehem.
[David departed] Sent time and again by his father to his brethren, by comparison from verse 17 (Piscator).
From Saul; either, 1. From Saul’s court; where having been entertained by Saul, to relieve him in his melancholy fits, he was permitted to go to his father’s house, to be sent for again upon occasion. Or, 2. From Saul’s camp, whither he used to come to visit his brethren; as appears from verse 17.
 Hebrew: וְדָוִד֩ בֶּן־אִ֙ישׁ אֶפְרָתִ֜י הַזֶּ֗ה מִבֵּ֥ית לֶ֙חֶם֙ יְהוּדָ֔ה וּשְׁמ֣וֹ יִשַׁ֔י וְל֖וֹ שְׁמֹנָ֣ה בָנִ֑ים וְהָאִישׁ֙ בִּימֵ֣י שָׁא֔וּל זָקֵ֖ן בָּ֥א בַאֲנָשִֽׁים׃ Circa 1595.  Genesis 24:1: “And Abraham was old, and well stricken in age (בָּ֖א בַּיָּמִ֑ים, he came in days): and the Lord had blessed Abraham in all things.”  John Buxtorf, Jr. (1599-1664) succeeded his father as Professor of Hebrew at Basel (1629-1664), and was perhaps the equal of his father in learning.  Anticritica: seu Vindiciæ Veritatis Hebraicæ Adversus Ludovici Cappelli Criticam quam Vocat Sacram.  The Complutensian Polyglot (taking its name from the university in Alcalá [Complutum, in Latin]; 1514) contained the first printed edition of the Septuagint, Jerome’s Vulgate, the Hebrew Text, Targum Onkelos with a Latin translation, and the first printed edition of the Greek New Testament. The labor of the scholars was superintended by Cardinal Francisco Ximénez de Cisneros.  Isaac Abarbanel (1437-1508) was one of the great Spanish Rabbis of his age and a stalwart opponent of Christianity, in spite of the danger. He held fast to a literal interpretation of the Scripture, over against Maimonides’ philosophical allegorizing. He commented on all of the Law and the Prophets.  Hebrew: וַיֵּ֙לְכ֜וּ שְׁלֹ֤שֶׁת בְּנֵֽי־יִשַׁי֙ הַגְּדֹלִ֔ים הָלְכ֥וּ אַחֲרֵי־שָׁא֖וּל לַמִּלְחָמָ֑ה וְשֵׁ֣ם׀ שְׁלֹ֣שֶׁת בָּנָ֗יו אֲשֶׁ֤ר הָלְכוּ֙ בַּמִּלְחָמָ֔ה אֱלִיאָ֣ב הַבְּכ֗וֹר וּמִשְׁנֵ֙הוּ֙ אֲבִ֣ינָדָ֔ב וְהַשְּׁלִשִׁ֖י שַׁמָּֽה׃  Hebrew: וְדָוִ֖ד ה֣וּא הַקָּטָ֑ן וּשְׁלֹשָׁה֙ הַגְּדֹלִ֔ים הָלְכ֖וּ אַחֲרֵ֥י שָׁאֽוּל׃  Hebrew: וְדָוִ֛ד הֹלֵ֥ךְ וָשָׁ֖ב מֵעַ֣ל שָׁא֑וּל לִרְע֛וֹת אֶת־צֹ֥אן אָבִ֖יו בֵּֽית־לָֽחֶם׃