Sahih Bukhari | Volume 5 | Hadith Number 265
Narrated by Ibn Abbas
During the last Hajj led by 'Umar, 'Abdur-Rahman bin 'Auf returned to his family at Mina and met me there. 'AbdurRahman said (to 'Umar), "O chief of the believers! The season of Hajj is the season when there comes the scum of the people (besides the good amongst them), so I recommend that you should wait till you go back to Medina, for it is the place of Migration and Sunna (i.e. the Prophet's tradition), and there you will be able to refer the matter to the religious scholars and the nobles and the people of wise opinions." 'Umar said, "I will speak of it in Medina on my very first sermon I will deliver there."