Musannaf Ibn Abi Shayba 1:881

Muhammad ibn Bishr al-‘Abdi narrated to us, he said: ‘Abdullah ibn ‘Amir narrated to us, from ‘Amr ibn Shu‘ayb, from his father, from his grandfather, who said: A woman called Busrah came to the Prophet, may Allah bless him and grant him peace, and said: "O Messenger of Allah, one of us sees that she is with her husband in a dream." He said: "If you find wetness, then perform ghusl, O Busrah."