But it was thou, a man mine equal - Margin, “a man according to my rank.” Septuagint, ἰσόψυχε isopsuche, equal-souled, like-souled, “second self” (Thompson); Vulgate, “unanimus,” of the same mind; Luther, “Geselle,” companion. The Hebrew word used here - ערך ‛êrek - means properly a row or pile, as of the showbread piled one loaf on another, Exodus 40:23; then it would naturally mean one of the same row or pile; of the same rank or condition. The word also means price, estimation, or value, Job 28:13; Leviticus 5:15, Leviticus 5:18; Leviticus 6:6. Here the expression may mean a man “according to my estimation, value, or price;” that is, of the same value as myself (Gesenius, Lexicon); or more probably it means a man of my own rank; according to my condition; that is, a man whom I esteemed as my equal, or whom I regarded and treated as a friend.
My guide - The word used here properly denotes one who is familiar - a friend - from the verb אלף 'âlaph - to be associated with; to be familiar; to be accustomed to. The noun is frequently used to denote a military leader - the head of a tribe - a chieftain; and is, in this sense, several times employed in Genesis 36 to denote the leaders or princes of the Edomites, where it is rendered duke. But here it seems to be used, not in the sense of a leader or a guide, but of a familiar friend.
And mine acquaintance - The word used here is derived from the verb to know - ידע yâda‛ - and the proper idea is that of “one well known” by us; that is, one who keeps no secrets from us, but who permits us to understand him thoroughly. The phrase “mine acquaintance” is a feeble expression, and does not convey the full force of the original, which denotes a more intimate friend than would be suggested by the word “acquaintance.” It is language applied to one whom we thoroughly “know,” and who “knows us;” and this exists only in the case of very intimate friends. All the expressions used in this verse would probably be applicable to Ahithophel, and to the intimacy between him and David.