Poole on 1 Samuel 23:14-18: A Covenant of Friendship (Revisited)
Verse 14:[1] And David abode in the wilderness in strong holds, and remained in (Ps. 11:1) a mountain in the wilderness of (Josh. 15:55) Ziph. And Saul (Ps. 54:3, 4) sought him every day, but God delivered him not into his hand.

[In a mountain of the wilderness of Ziph] Ziph pertains to the tribe of Judah (Jerome in Sanchez). This mountain was bordering on Idumea, as it is evident from Joshua 15:24; the steep mountains, and clefts of boulders, of this region are celebrated by Obadiah, Obadiah 3 (Menochius).
[On a mountain shaded] With trees (Menochius), or mists (Jerome in Menochius).
[He did not deliver him] The Holy Spirit says this: But Saul said, He has delivered. Thus was Saul mistaken in his opinion (Martyr).
But God delivered him not into his hand: As Saul fondly persuaded himself he intended, verse 7.
Verse 15:[2] And David saw that Saul was come out to seek his life: and David was in the wilderness of Ziph in a wood.

David saw; either by information from his spies, or by prospect from the top of the mountain where he was.
[In a Wood] Thus חֹרְשָׁה is translated (Jonathan, Syriac, Arabic, Pagnine, Montanus). In a wooded place (Junius and Tremellius). The ה is a locative suffix (certain interpreters in Malvenda).
Verse 16:[3] And Jonathan Saul’s son arose, and went to David into the wood, and strengthened his hand in God.
[Jonathan arose] Whom David informed through messengers, at what place and time he would expect him (Sanchez, similarly Martyr).
[He strengthened his hand in God (thus the Septuagint, Syriac, Junius and Tremellius, similarly Jonathan, Munster, Pagnine, Montanus)] In God, by the divine promises (Malvenda out of Junius).
Jonathan went where David had appointed to meet him at that time, and strengthened his hand in God; he comforted and supported him against all his fears, by minding him of God’s infallible promises made to him, and his singular providence which hitherto had and still would be with him.
Verse 17:[4] And he said unto him, Fear not: for the hand of Saul my father shall not find thee; and thou shalt be king over Israel, and I shall be next unto thee; and (1 Sam. 24:20) that also Saul my father knoweth.

[I shall be second to thee (thus Munster, Pagnine, Tigurinus), לְמִשְׁנֶה] For a second (Septuagint, Jonathan, Montanus).
I shall be next unto thee; which he gathered either from David’s generosity, ingenuousness, and true friendship to him; or from some promise made to him by David concerning it. Or the meaning of the words, next unto thee, may be as much as to say, I shall be under thee, after thee, or inferior to thee, as the phrase tibi secundus oft signifies. So that the whole imports thus much: I do not look to be king myself, (as by my birth I might expect,) but that thou shalt be king, (God having so appointed,) and I but in a secondary place inferior to thee.
[And Saul knows this] 1. From the prediction of Samuel. 2. From the success of David. 3. Because Jonathan and the people desire it (Martyr, similarly Menochius, Junius, Piscator). 4. From the speech of others, 1 Samuel 20:30, 31; 22:8 (Junius).
That also Saul my father knoweth, by strong and well-grounded conjectures, as hath been noted.
Verse 18:[5] And they two (1 Sam. 18:3; 20:16, 42; 2 Sam. 21:7) made a covenant before the LORD: and David abode in the wood, and Jonathan went to his house.
[They struck a covenant] Now for the third time. 1. Not out of fear, that one would repent of the deed; but out of love: for it pleases those loving to repeat the acts of love (Menochius). 2. The faith of men in its own nature is fluid and perishable: And so it is often needful to renew covenants. Here, Jonathan is little compliant to his father; rightly so, when he commands injustices, and things in conflict with the law of God (Martyr).
[Before the Lord] 1. With Jehovah as witness (Vatablus, thus Menochius). 2. Before Gad the Prophet, and Abiathar the Priest (Menochius, thus Junius, Piscator). 3. With God as author and arbiter (Junius, Piscator). Behold the modesty of Jonathan: He does not here recall the injuries that he had sustained for David’s sake (Martyr).
They two made a covenant, that is, renewed their former covenant before the Lord; setting themselves as in God’s presence, and calling upon him to be witness between them.
[1] Hebrew: וַיֵּ֙שֶׁב דָּוִ֤ד בַּמִּדְבָּר֙ בַּמְּצָד֔וֹת וַיֵּ֥שֶׁב בָּהָ֖ר בְּמִדְבַּר־זִ֑יף וַיְבַקְשֵׁ֤הוּ שָׁאוּל֙ כָּל־הַיָּמִ֔ים וְלֹֽא־נְתָנ֥וֹ אֱלֹהִ֖ים בְּיָדֽוֹ׃ [2] Hebrew: וַיַּ֣רְא דָוִ֔ד כִּֽי־יָצָ֥א שָׁא֖וּל לְבַקֵּ֣שׁ אֶת־נַפְשׁ֑וֹ וְדָוִ֥ד בְּמִדְבַּר־זִ֖יף בַּחֹֽרְשָׁה׃ [3] Hebrew: וַיָּ֙קָם֙ יְהוֹנָתָ֣ן בֶּן־שָׁא֔וּל וַיֵּ֥לֶךְ אֶל־דָּוִ֖ד חֹ֑רְשָׁה וַיְחַזֵּ֥ק אֶת־יָד֖וֹ בֵּאלֹהִֽים׃ [4] Hebrew: וַיֹּ֙אמֶר אֵלָ֜יו אַל־תִּירָ֗א כִּ֠י לֹ֤א תִֽמְצָאֲךָ֙ יַ֚ד שָׁא֣וּל אָבִ֔י וְאַתָּה֙ תִּמְלֹ֣ךְ עַל־יִשְׂרָאֵ֔ל וְאָנֹכִ֖י אֶֽהְיֶה־לְּךָ֣ לְמִשְׁנֶ֑ה וְגַם־שָׁא֥וּל אָבִ֖י יֹדֵ֥עַ כֵּֽן׃ [5] Hebrew: וַיִּכְרְת֧וּ שְׁנֵיהֶ֛ם בְּרִ֖ית לִפְנֵ֣י יְהוָ֑ה וַיֵּ֤שֶׁב דָּוִד֙ בַּחֹ֔רְשָׁה וִיהוֹנָתָ֖ן הָלַ֥ךְ לְבֵיתֽוֹ׃