In the weekly congregation in the blessed month of Rajab-ul-Murajjab, attendees should be made to recite the following supplication:

Reciting following supplication in the blessed month of Rajab is a Sunnah act; the Noblest Prophet صَلَّى اللهُ تَعَالٰى عَلَيْهِ وَاٰلِهٖ وَسَلَّم used to recite the following supplication when the blessed month of Rajab would commence:

اَللّٰهُمَّ  بَارِكْ  لَنَا  فِیْ  رَجَبٍ  وَّ  شَعْبَانَ  وَ  بَلِّغْنَا  رَمَضَان

Translation: O Allah (عَزَّوَجَلَّ)! Descend your Blessing upon us in the [blessed] months of Rajab and Sha’ban, and make us reach Ramadan.

(Al-Mu’jam-ul-Awsat, vol. 3, pp. 85, Hadees 3939)