Volume 3, Book 31, Number 138:
Narrated Abu Huraira:
Volume 3 – 436 / 1700
SAHIH BUKHARI VOLUME 3 > BOOK 31: FASTING
The Prophet said, “None of you should fast a day or two before the month of Ramadan unless he
has the habit of fasting (Nawafil) (and if his fasting coincides with that day) then he can fast that
day.”