Musnad Ahmad 937:75

Ya'la ibn 'Ubayd narrated to us, al-A'mash narrated to us, from 'Amr ibn Murrah, from Abu al-Bakhtari, from Abu Dharr, who said: I said: "O Messenger of Allah, the wealthy have taken away the reward; they pray, they fast, and they perform Hajj." He said: "And you pray, you fast, and you perform Hajj." I said: "They give charity, and we do not give charity." He said: "And within you is charity: your removing a bone from the road is charity, your guiding someone on the road is charity, your helping the weak with the excess of your strength is charity, your speaking on behalf of the one who has a speech impediment is charity, and your having intercourse with your wife is charity." He said: I said: "O Messenger of Allah, we satisfy our desire and are rewarded for it?" He said: "Do you see, if you were to place it in something forbidden, would you be sinful?" He said: I said: "Yes." He said: "So you count the evil, but you do not count the good?"