John Wesley on Leviticus 15:24

Seven days - If he did this ignorantly; but if the man and woman did this knowingly, being accused and convicted, they were punished with death, Lev 20:18, for as there was a turpitude in the action, so it was very prejudicial to the children then begotten, who were commonly weak, or leprous; which was also an injury to the commonwealth of Israel, and redounded to the dishonour of God and of the true religion, that the professors thereof gave such public evidence of their intemperance.