Sunan An-Nasa'i
Hadith #2941
It was narrated from Ibn Umar, that:when the Messenger of Allah performed Tawaf in Hajj and Umarah- as he first arrived (in Makkah), he would hasten in three rounds, and walk (at a regular pace) in four. Then he prayed two Rakahs, then he performed sai between As-Safa and Al-Marwah