Yahya related to me from Malik from Abu'zZinad from al-Araj from
Abu Hurayra that the Messenger of Allah, may Allah bless him and grant
him peace, said, "When you wake up from sleep to pray, wash your hands
before you put them in the wudu water, for you do not know where your
hands have spent the night."
Muwatta Malik Book 2, Hadith 7