Musnad Abu Ya'la al-Mawsili 160:145

Abu Bakr narrated to us, Ibn Fudayl narrated to us, from Abdullah bin Sa'id, from his grandfather, from Abu Hurayrah, from the Prophet (peace and blessings of Allah be upon him), who said: "When one of you prostrates, let him begin with his knees before his hands, and let him not kneel like the kneeling of a camel."