Musnad Ahmad 435:11

Yahya ibn Sa'id narrated to us, from Ibn 'Ajlan, who said: Muhammad ibn Yahya ibn Hibban informed me, from Ibn Muhayriz, from Mu'awiyah ibn Abi Sufyan, from the Prophet (peace and blessings of Allah be upon him), who said: "Do not hasten before me in bowing or in prostration, for whatever I precede you in when I bow, you will catch up with me when I rise; and whatever I precede you in when I prostrate, you will catch up with me when I rise. I have become bulky."