). This is exclusively an OT word. Accompanying the word “vow” is spiritual emphasis in the OT. A covenant people would naturally have repeated use for the concepts of pledge and vow.
Deuteronomy 24:10, 11, 12, 13 use the form עֲבוֹט, H6287, from the root, which means “to pawn” or “to lend on security.” A pledge, then, is something of value exchanged as security. This goes beyond the common concept of a pledge just as a verbal agreement.
The Gr. ἀρραβών, G775, a transliteration of the Sem. term, is used in the NT; “the guarantee of our inheritance” (Eph 1:14) and “the Spirit as a guarantee” (2 Cor 5:5).
International Standard Bible Encyclopedia (1915)
(1) The "pledge" is, as in modern English, security given for future payment (Ge 38:17-24) or conduct (Hab 2:6, where the conquered nations have given guaranties of their subserviency to the Chaldeans; the King James Version’s "thick clay" here rests on a misreading of the Hebrew). In 2Ki 18:23 (equals Isa 36:8) the "pledge" is a wager (so the Revised Version margin). Rabshakeh mockingly dares Hezekiah to stake a "pledge" that he can produce 2,000 men for the defense of Jerusalem, although the mighty Assyrian host has that number of horses alone. The general point of the obscure passage Pr 20:16 (equals 27:13) is that he who guarantees strangers needs a guaranty himself. 1Sa 17:18 is uncertain and the text may be corrupt. If not, the "pledge" is some (prearranged?) token of the welfare of David’s brethren.
(3) the American Standard Revised Version gives "pledge" for the King James Version and the English Revised Version "faith" in 1Ti 5:12.
See also EARNEST.