19 And he will make her take an oath, and say to her, If no man has been your lover and you have not been with another in place of your husband, you are free from this bitter water causing the curse; 20 But if you have been with another in place of your husband and have made yourself unclean with a lover: 21 Then the priest will put the oath of the curse on the woman, and say to her, May the Lord make you a curse and an oath among your people, sending on you wasting of the legs and disease of the stomach; 22 And this water of the curse will go into your body, causing disease of your stomach and wasting of your legs: and the woman will say, So be it.

Matthew Henry's Commentary on Numbers 5:19-22

Commentary on Numbers 5:11-31

(Read Numbers 5:11-31)

This law would make the women of Israel watch against giving cause for suspicion. On the other hand, it would hinder the cruel treatment such suspicions might occasion. It would also hinder the guilty from escaping, and the innocent from coming under just suspicion. When no proof could be brought, the wife was called on to make this solemn appeal to a heart-searching God. No woman, if she were guilty, could say "Amen" to the adjuration, and drink the water after it, unless she disbelieved the truth of God, or defied his justice. The water is called the bitter water, because it caused the curse. Thus sin is called an evil and a bitter thing. Let all that meddle with forbidden pleasures, know that they will be bitterness in the latter end. From the whole learn, 1. Secret sins are known to God, and sometimes are strangely brought to light in this life; and that there is a day coming when God will, by Christ, judge the secrets of men according to the gospel, Romans 2:16. 2 In particular, Whoremongers and adulterers God will surely judge. Though we have not now the waters of jealousy, yet we have God's word, which ought to be as great a terror. Sensual lusts will end in bitterness. 3. God will manifest the innocency of the innocent. The same providence is for good to some, and for hurt to others. And it will answer the purposes which God intends.