Musnad Abu Ya'la al-Mawsili 150:205

Dāwūd ibn ‘Amr ibn Zuhayr narrated to us, Ṣāliḥ ibn ‘Umar narrated to us, Muṭarrif narrated to us, from al-Sha‘bī, from Masrūq, from ‘Ā’ishah, who said: The Messenger of Allah (peace be upon him) would spend the night, and Bilāl would call him with the Adhān. He would then stand and perform ghusl, and I would see the water flowing down his skin and his hair. Then he would go out and pray, and I would hear his weeping. Then he would remain fasting throughout the day. I said to al-Sha‘bī: "In Ramaḍān?" He said: "It is the same."