Mishkat al-Masabih #1810

Aba Dharr reported God’s messenger as saying, “In every ascription of glory to God, every declaration of His greatness, every utterance of praise to Him, every declaration that He is the only God, in enjoining what is reputable, in forbidding what is objectionable, and in a man’s sexual intercourse there is sadaqa.” On being asked whether a reward would be given for satisfying one’s passion, he said, “Tell me; if he were to devote it to something forbidden, would it not be a sin on his part? Similarly, if he were to devote it to something lawful, he would have a reward.” Muslim transmitted it.