Sahih Muslim
The Book of Pilgrimage (Kitab Al-Hajj)
Book Number: 007 / Hadith Number: 3007
Nafi' reported that Ibn 'Umar regarded halt at Muhassab as Sunnah (of the Holy Prophet) and observed the noon prayer on Yaum al-Nafr at that place. Nafi' said: Allah's Messenger (may peace be upon him) halted at Muhassab and the Caliphs did the same after him.