‘Abdullāh ibn Muḥammad reported to us, he said: ‘Abd al-Ṣamad reported to me, he said: Shu’bah reported to me, he said: Abū Bakr ibn Ḥafṣ reported to me, he said: I heard Abū Salamah say:

I and the brother of ‘Ā’ishah bint Abī Bakr (may Allāh be content with her) went to her. Her brother asked her about the Ghusl of the Prophet Muhammad ﷺ. So, she requested a vessel containing approximately four litres of water. Then, she performed Ghusl and poured water over her head, while there was a veil between us and her.

Imām Abū ‘Abdullāh (al-Bukhārī) said: Yazīd ibn Hārūn, Bahz, and al-Judayy narrated from Shu’bah that it was approximately four litres