صحيح مسلم

Abu Dharr reported: some of the people from among the Companions of the Messenger of Allah (ﷺ) said to him: Messenger of Allah, the rich have taken away (all the) reward. They observe prayer as we do; they keep the fasts as we keep, and they give Sadaqa out of their surplus riches. Upon this he (the Holy Prophet) said: Has Allah not prescribed for you (a course) by following which you can (also) do sadaqa? In every declaration of the glorification of Allah (i. e. saying Subhan Allah) there is a Sadaqa, and every Takbir (i. e. saying Allah-O-Akbar) is a sadaqa, and every praise of His (saying al-Hamdu Lillah) is a Sadaqa and every declaration that He is One (La illha ill-Allah) is a sadaqa, and enjoining of good is a sadaqa, and forbidding of that which is evil is a Sadaqa, and in man's sexual Intercourse (with his wife, ) there is a Sadaqa. They (the Companions) said: Messenger of Allah, is there reward for him who satisfies his sexual passion among us? 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 should have a reward.