Sahih Al Bukhari Hadith Number 1768

Narrated Khalid bin Al-Harith: ‘Ubaidullah was asked about Al Mahassab. ‘Ubaidullah narrated: Nafi` said, ‘Allah’s Messenger (peace be upon him)s, `Umar and Ibn `Umar camped there.” Nafi` added, “Ibn `Umar used to offer the Zuhr and `Asr prayers at it (i.e. Al-Mahassab).” I think he mentioned the Maghrib prayer also. I said, “I don’t doubt about `Isha’ (i.e. he used to offer it there also), and he used to sleep there for a while. He used to say, ‘The Prophet (peace be upon him) used to do the same.’ “