In the Name of Allah, Most Gracious, Most Merciful.
All praise is due to Allah, and peace and blessings be upon His Messenger.
Brother, thank you for such an important question. May Allah Almighty bless you and we pray to have all our efforts rendered for the sake of Allah.
No doubt that Muslims are urged to strive hard in getting close to Allah with all forms of acts of worship; they should take that as a top priority. However, they are instructed that whatever they do, they should not deviate from the teachings and principles set by the noble Prophet, Muhammad (peace and blessings be upon him). He has set for us a shinning model that we should follow in order to keep firm on the right path. Therefore it’s very important for a committed Muslim to make sure that his acts of worship have basis both in the Qur’an and the Sunnah of the Prophet (peace and blessings be upon him).
In this regard, the prominent Muslim scholar Sheikh Yusuf Al- Qaradawi states:
The Prophet (peace and blessings of Allah be upon him) was keen on fasting in the month of Sha`ban more than he was in other months. `A'ishah (may Allah be pleased with her) reported that the Prophet (peace and blessings of Allah be upon him) never fasted for a whole month except in Ramadan. This refutes what some people do; observing fast for three consecutive months: Rajab, Sha`ban and Ramadan, followed by six days of Shawwal . That is, they start fasting at the beginning of Rajab until the seventh of Shawwal, leaving nothing but the Day of `Eidul-Fitr. Neither the Prophet (peace and blessings of Allah be upon him) nor his Companions or even their successors were reported to have done so.
The Prophet (peace and blessings of Allah be upon him) used to fast some days of every month. `A'ishah (may Allah be pleased with her) said that the Prophet (peace and blessings of Allah be upon him) sometimes would observe fasting continuously, to the extent that his Companions thought he would never break fast, and in other times he would refrain from fasting to the extent that they thought he would never fast again.
The Prophet (peace and blessings of Allah be upon him) usually observed fasting on Mondays and Thursdays and three days of each month (the 13th , 14th and 15th). He sometimes used to fast every alternate day, following the pattern of Prophet Dawud (peace be upon him). He even made this clear: “The best way of fasting in Allah’s sight is that of Dawud, who used to observe fasting every alternate day.”
The Prophet (peace and blessings of Allah be upon him) used to observe fasting in Sha`ban more than he did in other months. This was a kind of self-preparation for the coming of Ramadan; that is, to act as some sort of girding oneself for Ramadan. But there are no textual evidence that there are specific days in Sha`ban in which fasting is commendable. It is, by and large, impermissible for one to prefer certain days to observe voluntary fasting or certain nights to perform Night Prayers, lacking any juristic basis for that action. Religious acts are not left for man’s whims. Rather, they are subject to Divine legislation. Thus, specifying certain times and places for worship and the description of different acts of worship are the matters of the Divine, not that of human.
Allah Almighty knows best.