Musnad Ahmad 944:16

Abdullah ibn Yazid narrated to us, Haywah and Ibn Lahi'ah narrated to us, they said: Hassan, the freed slave of Muhammad ibn Sahl, narrated to us, from Sa'id ibn Abi Hilal, from Abdullah ibn Ali, from Harmi ibn Amr al-Khatmi, from Khuzaymah ibn Thabit, the companion of the Messenger of Allah, may Allah bless him and grant him peace, that the Messenger of Allah, may Allah bless him and grant him peace, said: "Indeed, Allah is not ashamed of the truth. Do not approach women in their posteriors."