Musannaf Ibn Abi Shayba 1:1220

Abu Bakr narrated to us, he said: Jarir narrated to us, from Qabus, from his father, from Ibn Abbas, who said: It is disliked that Allah be mentioned while one is sitting on the toilet, and [while] a man is having intercourse with his wife, because He is the Possessor of Majesty, and He is too exalted for that.