Musnad Ahmad 32:1366

Hujayn ibn al-Muthanna narrated to us, Abd al-Aziz—meaning Ibn Abi Salamah al-Majishun—narrated to us, from Ishaq ibn Abdullah ibn Abi Talhah, from Anas, who said: The Prophet, peace and blessings of Allah be upon him, used to enter the house of Umm Sulaym and sleep on her bed while she was not in it. He said: So he came one day and slept on her bed. Then she was brought, and it was said to her: "This is the Prophet, peace and blessings of Allah be upon him, sleeping in your house on your bed." He said: So she came while he was sweating, and his sweat had pooled on a piece of leather on the bed. He said: So she opened her bag, and she began to soak up that sweat and wring it into her bottles. The Prophet, peace and blessings of Allah be upon him, was startled and said: "What are you doing, O Umm Sulaym?" She said: "O Messenger of Allah, we hope for its blessing for our children." He said: "You have done right."