Abu Dawud Book 2, Hadith Number 1280.

Chapter : Prayer in the forenoon.

Narated By Abu Dharr : The Prophet (PBUH) said: In the morning alms are due from every bone in man’s body. His salutation to everyone he meets is alms; his enjoining good is alms; his forbidding what is evil is alms; the removal of a harmful thing from the way is alms; to have sexual intercourse with one’s wife is alms; and two rak’ahs which one prays in the forenoon serve instead of that.

Abu Dawud said: The tradition narrated by ‘Abbad is more perfect (than the version narrated by Musaddad). Musaddad did not mention in his version “the command (of good) and the prohibition (of evil)”. Instead he added in his version saying: “Such and such”. Ibn Ma’an added in his version: “They (the people) said: Apostle of Allah (PBUH), how is it that one of us fulfils his desire and still there are alms for him (i.e. is rewarded)? He replied: What do you think if he had unlawful sexual intercourse; would he not have been a sinner?