Musannaf Ibn Abi Shayba 27:588

Waki’ narrated to us, he said: Al-Mas’udi narrated to us, from ‘Abd al-Malik ibn ‘Umayr, from Abu al-Malih al-Hudhali, he said: ‘Abdullah used to screen the Prophet, may Allah bless him and grant him peace, when he performed ghusl, and he would wake him up when he slept, and he would walk with him on the earth.