It is narrated from Sayyidah Aishah (may Allah be pleased with her); she said: I set out with the Messenger of Allah (peace and blessings be upon him) on a journey. He (peace and blessings be upon him) halted at a place and said to his companions: "Go on ahead." Then he said to me: "Come, let us race." So I raced him (peace and blessings be upon him) and I got ahead. Then, after that, I set out with him (peace and blessings be upon him) on another journey, and by then I had put on weight. We halted at a place, and he (peace and blessings be upon him) said to his companions: "Go on ahead." Then he said: "Come, let us race." So I raced him (peace and blessings be upon him), and he (peace and blessings be upon him) got ahead of me. Then he (peace and blessings be upon him) patted me between my shoulders and said: "This is for that."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19428