Abu Dawud Book 4, Hadith Number 1717.
Chapter : Not known.
Narated By Aqra’ ibn Habib : Ibn Abbas said: Aqra’ ibn Habis asked the Prophet (PBUH) saying: Apostle of Allah hajj is to be performed annually or only once? He replied: Only once, and if anyone performs it more often, he performs a supererogatory act.