The Grand Ayatollah Makarem answered a question about fasting during the months of Rajab and Sha’aban.
Question: What is the ruling on fasting during the months of Rajab and Sha’aban?
The Grand Ayatollah Makarem: It is Mostahab to fast the whole of the months of Rajab and Sha’aban; and if that cannot be done, fast some days of these months, even if it is for one day.