Ante-Nicene Fathers, Vol VIII:
Pseudo-Clementine Literature.: Chapter XXX

Chapter XXX.—“Whatsoever Things are Pure.”

“But who is there to whom it is not manifest that it is better not to have intercourse with a woman in her separation, but purified and washed.  And also after copulation it is proper to wash.  But if you grudge to do this, recall to mind how you followed after the parts of purity when you served senseless idols; and be ashamed that now, when it is necessary to attain, I say not more, but to attain the one and whole of purity, you are more slothful.  Consider, therefore, Him who made you, and you will understand who He is that casts upon you this sluggishness with respect to purity.