The sacred month of Ramadan is ahead; a month in which you should strengthen yourself morally. There is a tradition attributed to the Noble Messenger about informing the people of the advent of the blessed month of Ramadan. One of the phrases is:" You have been invited to God's feast." The difference between God's feast and peoples' feasts is that when you go to a feast, you will have some items of food to eat and means of entertainment befitting your status. But in God's feast, one part is to observe the fast. Another important item which is a] spiritual [meal from the Unseen, is the Holy Qur'an. You have been invited to His feast; you are His guest in the month of Ramadan. Your host has compelled you to fast. Block those avenues that lie open to worldly considerations and lusts so that you are prepared for the "Laylatuul-Qadr".
The month of Sha`ban is the prelude to the holy month of Ramadan. It prepares the people for the holy month and for the feast of God. When you want to go to a party, you do not go in your usual, everyday dress. You normally dress up in another way and attend the party in a different manner. You modify your manners from what they might be when you are at home. The month of Sha`ban is the time for that preparation before attending the party, just as you get ready and make yourself look a bit different from the way you appear in your house. Sha`ban is the month that prepares these people; these Muslims, for" God's Feast". And the manner of preparation lies in the "Munajat-e Sha`baniyyah". I have not seen any other supplication that has been said to have been recited by all the Imams, as is the case with this Sha`baniyyah Supplication. This supplication is unique in this regard; I do not recall any other one that the Imams used to recite. The purpose of this Sha`baniyyah Supplication is to prepare you and everyone for" God's Feast".
Sahifeh-ye Imam, vol.13, p. 28