Musnad Ahmad 1153:799

Abu Nu'aym narrated to us, Zakariya narrated to us, from 'Amir, from 'Abd al-Rahman ibn al-Harith ibn Hisham, from 'Aishah: "Bilal used to come to the Messenger of Allah (peace and blessings of Allah be upon him) and inform him of the prayer while he was in a state of major ritual impurity (junub). So he would stand up, perform ghusl, then come to the mosque and pray, and I would hear his recitation while his head was dripping [with water]. Then he would fast that day."