Abu Dawud
Jihad
Book Number: 008 / Hadith Number: 2572
Narated By 'Aisha, Ummul Mu'minin : while she was on a journey along with the Apostle of Allah (pbuh): I had a race with him (the Prophet) and I outstripped him on my feet. When I became fleshy, (again) I had a race with him (the Prophet) and he outstripped me. He said: This is for that outstripping.