Ibn Al Qayyim said:
“There are three points about fasting the month of Shaban more than other months:
First: Prophet Muhammad (peace be upon him) used to fast three days every month. Perhaps he was busy and could not fast in some months, so he gathered all these in Sha’ban to fast them before the obligatory fast.
Second: He may have done so to honor Ramadan. This fast is similar to the regular voluntary prayers before the obligatory ones to honor them.
Third: It is a month when deeds are raised to Allah The Almighty. Thus, Prophet Muhammad liked his deeds to be raised while he was fasting.”
What follows are some of the authentic hadiths related to fasting in the blessed month of Shaban.
Deeds are Raised to Allah
Usamah ibn Zaid said:
“I said: ‘O Messenger of Allah, I do not see you fasting any month as much as Sha’ban.’
He said: "That is a month to which people do not pay much attention, between Rajab and Ramadan. It is a month in which the deeds are taken up to the Lord of the worlds, and I like that my deeds be taken up when I am fasting" (An-Nasa’i).
Blessings of Fasting in Shaban
Umm Salamah narrated:
I did not see the Prophet fasting two consecutive months except for Sha’ban and Ramadan (Tirmidhi)
Aisha (May Allah be pleased with her) reported:
In another narration, she says:
He observed Saum during the whole month of Sha’ban except a few days (Al Bukhari and Muslim).
Prophet Muhammad said:
Do not precede Ramadan by fasting the day or two before it (Ahmad).
Making Up the Missing Fasts
I would not make up what was due upon me from Ramadan except in Sha’ban, until the Messenger of Allah died (Tirmidhi)
She said in another narration:
If I had some part of the fast of Ramadan to make up, I would not be able to atone for it except in Sha’ban (Abu Dawud)
If one amongst us had to break fasts (of Ramadan due to natural reasons, i.e. menses) during the life of the Messenger of Allah she could not find it possible to complete them so long she had been in the presence of Allah’s Messenger till Sha’ban commenced (Muslim)
Honor of Ramadan
Anas narrated that:
The Prophet was asked which fast was most virtuous after Ramadan?
He said: "Sha’ban in honor of Ramadan".
He said: “Which charity is best?”
He said: "Charity in Ramadan" (Tirmidhi)
It was narrated that ‘Ali ibn Abi Talib said:
“The Messenger of Allah said:
‘When it is the night of the middle of Sha’ban, spend its night in prayer and observe a fast on that day. For Allah descends at sunset on that night to the lowest heaven and says: ‘Is there no one who will ask Me for forgiveness, that I may forgive him? Is there no one who will ask Me for provision, that I may provide for him? Is there no one who is afflicted by trouble, that I may relieve him?’ And so on, until dawn comes.’” (Ibn Majah)
In another Hadith, he said:
On the night of mid-Sha’ban, Allah looks at His creation and forgives all of them except for the polytheist and the quarrelsome (Ibn Majah)
Source: About Islam