Musnad Ahmad 1153:610

Bahz narrated to us, he said: Shu'bah narrated to us, he said: Ash'ath ibn Sulaym informed me, he said: He heard his father narrating from Masruq, from 'Aishah, that she said: "The Messenger of Allah, peace and blessings of Allah be upon him, used to love starting with the right in all his affairs as much as he was able: in his purification, in combing his hair, and in putting on his sandals." He said: Then when Ash'ath came to Kufa, he said: "The Messenger of Allah, peace and blessings of Allah be upon him, used to love starting with the right as much as he was able."