Ecclesiastes 5:4 - Matthew Poole's English Annotations on the Holy Bible

A vow; which is a solemn promise, whereby a man binds himself to do something which is in his power to do. Defer not to pay it; perform it whilst the sense of thine obligation is fresh and strong upon thee, lest either thou seem to repent of thy promises, or lest delays end in denials and resolutions of non-performance. See Numbers 30:2 Deuteronomy 23:21 Psalms 66:13,14 Psalms 66:11. In fools; in hypocritical and perfidious persons, who, when they are in distress, make liberal vows, and when the danger is past, neglect and break them; whom he calls fools, partly because it is the highest folly to despise and provoke, to think to mock and deceive, the all-seeing and almighty God; and partly in opposition to the contrary opinion of such persons, who think they deal wisely and cunningly in serving themselves of God, by getting the advantage or deliverance which they desire by making such vows, and yet avoiding the inconvenience and charge of payment when once the work is done, whereas nothing is more impious or ridiculous than such an imagination.