Ubaidullah bin 'Umar bin Hafs عبيد الله بن عمر بن حفص بن عاصم · The Book on Purification

"One day I climbed on Hafsah's house, and I saw the Prophet relieving himself while facing Ash-Sham, with his back toward the Ka'bah."

"The Prophet was asked about a man who finds wetness and he does not remember having a wet dream. So he said: 'He is to perform Ghusl. And (he was asked) about a man who had a wet dream but does not find any wetness, so he said: 'No Ghusl is required of him.' Umm Salamah said: 'O Messenger of Allah! Is the woman required to perform Ghusl if she sees that?' He replied: 'Yes. Indeed women are the partners…

he asked the Prophet: "Can one of us sleep while he is Junub?" So he replied: "Yes, when he performs Wudu."