They shall both bathe themselves - What a wonderful tendency had these ordinances to prevent all excesses! The pains which such persons must take, the separations which they must observe, and the privations which, in consequence, they must be exposed to in the way of commerce, traffic, etc., would prevent them from making an unlawful use of lawful things.

The woman also with whom man shall lie with seed of copulation,.... It seems to respect any congress of a man and woman, whether in fornication or adultery, or lawful marriage, and particularly the latter; for though marriage is honourable and holy, and carnal copulation in itself lawful, yet such is the sinfulness of nature, that as no act is performed without pollution, so neither that of generation, and by which the corruption of nature is propagated, and therefore required a ceremonial cleansing:
they shall both bathe themselves in water, and be unclean until the even; so Herodotus (f) reports, that as often as a Babylonian man lay with his wife, he had used to sit by consecrated incense, and the woman did the same: and in the morning they were both washed, and did not touch any vessel before they had washed themselves; and he says the Arabians did the like: and the same historian relates (g) of the Egyptians, that they never go into their temples from their wives unwashed; see Exodus 19:15.
(f) Clio, sive, l. 1. c. 198. (g) Euterpe, sive, l. 2. c. 64.

Sexual connection. "If a man lie with a woman with the emission of seed, both shall be unclean till the evening, and bathe themselves in water." Consequently it was not the concubitus as such which defiled, as many erroneously suppose, but the emission of seed in the coitus. This explains the law and custom, of abstaining from conjugal intercourse during the preparation for acts of divine worship, or the performance of the same (Exodus 19:5; 1-Samuel 21:5-6; 2-Samuel 11:4), in which many other nations resembled the Israelites. (For proofs see Leyrer's article in Herzog's Cyclopaedia, and Knobel in loco, though the latter is wrong in supposing that conjugal intercourse itself defiled.)

A man - Or, The man, that had such an issue, which is plainly to be understood out of the whole context. For though in some special cases relating to the worship of God, men were to forbear the use of the marriage - bed, yet to affirm that the use of it in other cases did generally defile the persons, and make them unclean till even, is contrary to the whole current of scripture, which affirms the marriage - bed to be undefiled, Hebrews 13:4, to the practice of the Jews, which is a good comment upon their own laws, and to the light of nature and reason.