1 Corinthians 7:6

But this I say by way of concession, not of commandment. [That his readers may understand his counsel, Paul discusses the marriage state, and shows that the reciprocal rights of the parties thereto forbid abstinence to either husband or wife, save in cases where one wishes to devote a season to prayer; but even here the abstinence must be by mutual consent, and the apostle does not enjoin it, but merely concedes or permits it at such times, because the higher duty of prayer may for a season suspend conjugal duty. But here again caution must be observed, lest too prolonged abstinence might work temptation to either party, especially the prayerless one.]