That which is gone out of thy lips thou shalt keep and perform,.... Which were in their power to perform and lawful to do; and this is observed to make them watchful and cautious, and not be rash in making vows, since, when once they were made, an exact and rigid performance of them was expected; see Ecclesiastes 5:4,

even a freewill offering, according as thou hast vowed unto the Lord thy God, which thou hast promised with thy mouth; be it what it will, as to the matter of it, it was to be paid, and in the manner as it was vowed and promised. Aben Ezra observes, that every vow is a freewill offering, but not every freewill offering a vow; the Targum of Jonathan enumerates the several things to be performed, sin offerings, trespass offerings, burnt offerings, and oblations of holy things, and drink offerings, and gifts of the house of the sanctuary, and alms to the poor.

That which is gone out of thy lips thou shalt {m} keep and perform; even a freewill offering, according as thou hast vowed unto the LORD thy God, which thou hast promised with thy mouth.

(m) If the vow is lawful and godly.

23:23 A free - will - offering - Which though thou didst really make, yet being made, thou art no longer free, but obliged to perform it.

23:15-25 It is honourable to shelter and protect the weak, provided they are not wicked. Proselytes and converts to the truth, should be treated with particular tenderness, that they may have no temptation to return to the world. We cannot honour God with our substance, unless it be honestly and honourably come by. It must not only be considered what we give, but how we got it. Where the borrower gets, or hopes to get, it is just that the lender should share the gain; but to him that borrows for necessary food, pity must be showed. That which is gone out of thy lips, as a solemn and deliberate vow, must not be recalled, but thou shalt keep and perform it punctually and fully. They were allowed to pluck and eat of the corn or grapes that grew by the road side; only they must not carry any away. This law intimated what great plenty of corn and wine they should have in Canaan. It provided for the support of poor travellers, and teaches us to be kind to such, teaches us to be ready to distribute, and not to think every thing lost that is given away. Yet it forbids us to abuse the kindness of friends, or to take advantage of what is allowed. Faithfulness to their engagements should mark the people of God; and they should never encroach upon others.