Reference: http://binothaimeen.net/content/1372
al-Liqaa ash-Shahree – Tape No.60
Question: Has it been [authentically] confirmed that the Prophet (sal-Allaahu ‘alayhi wa sallam) would fast during the month of Sha’baan?
Response: The Prophet (sal-Allaahu ‘alayhi wa sallam) would increase in fasting during the month of Sha’baan, such that he would fast most of it except for a day or two. So, because of that, it is befitting for the Muslim to increase in fasting during the month of Sha’baan.