It is narrated from Rasool Allah-saww that when (a momin) fasts for thirty days in the month of Rajab, a Divine caller announces, O Servant of Allah-azwj, as far as your previous deeds are concerned you have been pardoned for your sins, so you better focus your attention on the (enhancement of) future deeds, and Allah-azwj has Blessed you with bounties of all of Paradises, which are like 40,000 cites made out of gold, each city consisting of 40,000 palaces, …….
Someone asked Rasool Allah-saww, how about someone, due to weekness or illness or a lady out of impurity, is able to fast during the month of Rajab. Is there any substitute for him/her to reap these rewards? Prophet-saww replied: ‘Yes, every day donate a bread as a ‘Saddaqa’ (charity) to a ‘Masqeen’ (deprived), I say it in the name of that Who Posses my soul, when he acts this way, he would achieve these rewards which I have describes above and even more than that. Indeed, if all inhabitants of the earth and heavens would collectively strive to level those rewards which he has secured in the Paradise then they would not succeed. (Ref. Sawab ul Amaal wa Aqab ul Amaal, pp. 62, haith no. 4, Bihar ul Anwar, vol. 94, pp.31, Wasailushia, vol. 10, pp. 483, Rawzatal Waizeen, vol. 2, pp.58).