Musannaf Ibn Abi Shayba 1:828

Isma'il ibn 'Ulayyah narrated to us, from Hajjaj ibn Abi 'Uthman, he said: Yahya ibn Abi Kathir narrated to us, he said: Abu Kathir narrated to me, he said: I said to Abu Hurayrah: "A man performs ghusl (ritual bath) from janabah (major ritual impurity), then he lies down with his wife." He said: "There is no harm in it."