Abu Dawud
Prayer
Book Number: 002 / Hadith Number: 1277
Narated By Anas b. Malik : I offered two rak'ahs of prayer before the sunset prayer (i.e. obligatory) during the time of the Apostle of Allah (pbuh). I (the narrator al-Mukhtar b. Fulful) asked Anas: Did the Apostle of Allah (pbuh) see you? He replied: Yes, but he neither commanded us nor forbade us (to do so).