Musnad Ahmad 937:184

'Arim and 'Affan narrated to us, they said: Mahdi ibn Maymun narrated to us, Wasil, the freed slave of Abu 'Uyaynah, narrated to us, from Yahya ibn 'Aqil, from Yahya ibn Ya'mar, from Abu al-Aswad al-Du'ali, from Abu Dharr, who said: They said: "O Messenger of Allah, the wealthy have taken away the rewards; they pray as we pray, they fast as we fast, and they give charity from their surplus wealth." He said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Has Allah not provided you with that which you may give as charity? Indeed, in every *tasbihah* (saying *SubhanAllah*) is a charity, in every *tahmidah* (saying *Alhamdulillah*) is a charity, and in the sexual intercourse of one of you is a charity." He said: They said: "O Messenger of Allah, does one of us satisfy his desire and have a reward in it?" He said: "Do you see, if he were to place it in the forbidden, would he have a sin upon him for it? Likewise, if he places it in the lawful, he has a reward for it." 'Affan said: "You give charity," and he said: "And a *tahlilah* (saying *La ilaha illallah*) and a *takbirah* (saying *Allahu Akbar*) is a charity, enjoining good is a charity, forbidding evil is a charity, and in sexual intercourse..."