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 Ecc 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.