Musnad Ahmad 1153:536

Muhammad ibn Mus'ab narrated to us, he said: Al-Awza'i narrated to us, from Al-Zuhri, from 'Urwah, from 'Aishah, she said: "The Messenger of Allah (peace and blessings of Allah be upon him) was never given a choice between two matters in Islam, except that he chose the easier of the two."