The Ruling on Fasting in Rajab and Sha'ban

Question:
May Allah bless you. The questioner says: One of our grandmothers fasts in Rajab and Sha'ban, believing that these are the best months. What is the ruling on this?

Answer:
As for fasting in Rajab, nothing has been reported regarding it. As for fasting in Sha'ban, it has been reported that the Prophet (peace and blessings be upon him) fasted most of it. Therefore, it is recommended to fast most of Sha'ban, but not the entire month. As for Rajab, nothing has been reported regarding it, so fasting in it, or fasting part of it, is considered a religious innovation (bid'ah) because there is no evidence for it. This is except for one who has a continuous habit of voluntary fasting; in that case, he fasts in Rajab along with the other months. However, if he specifically intends to fast in Rajab and singles it out for fasting over other months, that is considered a religious innovation. Yes.