Moses argued with himself. Moses said: A man of Israel may have gone to his wife, and they will be found to be prevented from receiving the Torah. What did he do? He added one day (more) for them on his own account, so that if a man of Israel went to his wife they would be found to be clean for two (complete) days; therefore he added one day for them on his own account.
The Holy One, blessed be He, said to him: Moses! How many souls of the children of men would have come forth from Israel in that night? What thou hast done has been (rightly) accomplished. The Holy One, blessed be He, approved his action.