Musnad Abu Ya'la al-Mawsili 140:27

Ibrahim ibn al-Hajjaj al-Sami narrated to us, Hammad ibn Salamah narrated to us, from Yazid al-Raqashi, from Anas ibn Malik: That the Messenger of Allah (peace be upon him) intended to pray over Abdullah ibn Ubayy. So, Gabriel took hold of his garment and said: "Do not pray over any of them, ever, and do not stand at his grave." (At-Tawbah)