Asim al-Ahwal عاصم الأحول · Fasting (Kitab Al-Siyam)

I and Masruq entered upon 'Aishah and we said: Mother of believers, there are two persons from the Companions of the Muhammad (ﷺ). One of them hastens to break the fast and hastens to pray while the other delays to break the fast and delays praying. She asked: Which of them hastens to break the fast and hasten to pray ? We replied: 'Abd Allah (b. Mas'ud). She said: Thus did the Messenger of Allah (ﷺ) do.

The Messenger of Allah (ﷺ) used to command us to fast the days of the white (nights): thirteenth, fourteenth and fifteenth of the month. He said: This is like keeping perpetual fast.