1 Corinthians 7:5 - Matthew Poole's English Annotations on the Holy Bible

Defraud not one the other; that is: Withhold not yourselves one from another; which he rightly calls defrauding one another, because he had before declared it a debt; and further declared, that neither the husband nor the wife had a power over their own bodies, but the power of either of their bodies was in their correlate. He adds, except it be with consent, mutual consent, and then it is indeed no defrauding; and for a time, for a religious end, that they might give themselves to fasting and prayer: not that this abstinence is necessary to us by any Divine precept, to prepare us for solemn prayer, (for such only is here spoken of), for then the apostle would not have made consent necessary in this case; but the Jews were commanded it, Exodus 19:15, as a preparation to their hearing of the law; and it was a piece of the legal purification, as appeareth from 1 Samuel 21:4, as to which Christians were at liberty, and might observe or not observe it, as they agreed. And come together again, that Satan tempt you not for your incontinency: then he requires, that they should return to their former course, not defrauding one another, lest the devil, observing their abstinence, should tempt them to unlawful mixtures, seeing their inability to contain themselves within the bounds of temperance and chastity.