Is it permissible to fast on Mondays and Thursdays in the month of Rajab without the intention of singling it out?

Question:
He says: Honorable Shaykh, may Allah grant you success, if I fast on a Monday or Thursday in the month of Rajab, is my fast valid or is it…

Answer:
Fasting on Mondays and Thursdays is a recommended practice (sunnah) in every month, whether Rajab or otherwise. If you single out Rajab and say, “I do not fast on Mondays and Thursdays except in Rajab,” that is a religious innovation (bid'ah). But if it is your habit to fast on Mondays and Thursdays every week, in Rajab and in other months, there is nothing wrong with it. Yes.