Musnad Ahmad 658:47

'Affan narrated to us, Shu'bah narrated to us, Al-Hakam narrated to me, from Ibn Abi Layla, from Al-Bara': "That the Prophet, peace and blessings of Allah be upon him, when he would bow, and when he would raise his head from bowing, and his prostration, and what was between the two prostrations, [they were] nearly equal."