Abu Ja'far al-Nafaili عبد الله بن محمد أبو جعفر النفيلي الحران · The Book of Ghusl and Tayammum

"I entered upon 'Aishah and asked her: 'Did the Messenger of Allah (ﷺ) perform Ghusl at the beginning of the night or at the end?' She said: 'Both. Sometimes he performed Ghusl at the beginning and sometimes at the end.' I said: 'Praise be to Allah who has made the matter flexible.'"