Musannaf Ibn Abi Shaybah

Hazrat Urwah narrates that Hazrat Abdullah bin Arqam set out with his companions with the intention of performing Umrah. They gave the call to prayer (adhan) and the iqamah, then he said to one of his companions, "Go ahead and lead the prayer, because I heard the Messenger of Allah (peace and blessings be upon him) say: 'When the time for prayer comes and any of you feels the need to relieve himself, then he should first relieve himself.'"