Sahih al-Bukhari 1660

Narrated Salim:`Abdul Malik wrote to Al-Hajjaj that he should not differ from Ibn `Umar during Hajj. On the Day of `Arafat, when the sun declined at midday, Ibn `Umar came along with me and shouted near Al- Hajjaj's cotton (cloth) tent. Al-Hajjaj came Out, wrapping himself with a waist-sheet dyed with safflower, and said, "O Abu `Abdur-Rahman! What is the matter?" He said, If you want to follow the Sunna (the tradition of the Prophet (p.b.u.h) ) then proceed (to `Arafat)." Al-Hajjaj asked, "At this very hour?" Ibn `Umar said, "Yes." He replied, "Please wait for me till I pour some water over my head (i.e. take a bath) and come out." Then Ibn `Umar dismounted and waited till Al-Hajjaj came out. So, he (Al-Hajjaj) walked in between me and my father (Ibn `Umar). I said to him, "If you want to follow the Sunna then deliver a brief sermon and hurry up for the stay at `Arafat." He started looking at `Abdullah (Ibn `Umar) (inquiringly), and when `Abdullah noticed that, he said that he had told the truth.