Musannaf Ibn Abi Shayba 1:678

Yazid ibn Harun narrated to us, from Hammad ibn Salamah, from Ata al-Khurasani, from Yahya ibn Ya'mar, from Ammar, from the Prophet (may Allah bless him and grant him peace), that he granted a concession to the person in a state of major ritual impurity (junub), if he wishes to sleep, eat, or drink, to perform ablution (wudu) like his ablution for prayer.