Imam As-Sadiq (peace be upon him) reports that the Prophet Mohammad (prayers and Allah's peace be upon him and his holy Household) said: “Rajab is the month of asking forgiveness [from God] for my nation, so ask for forgiveness in abundance. Verily, He is the Most-forgiving, the Most-merciful. Rajab is called “Rajab”, because mercy on my nation is poured down a thorough pouring. Therefore, say in abundance: 'Astaghfirullaha wa as'aluhū al-tawbah' (I ask forgiveness from God and ask Him [to enable me for] repentance).
The late Sheikh Abbas Al-Qummi in his Mafaātih al-Jinan quotes the Prophet Muhammad (prayers and Allah's peace be upon him and his holy Household) as saying: "Verily Rajab is the great month of God. No other month resembles it in its honour and merit. Fighting against infidels is forbidden. Beware, verily Rajab is God's month and Sha'ban is my month and [the month of] Ramadan is my nations month. Beware whoever fasts a day in Rajab greatest divine pleasure will become decisive for him and divine wrath will go away from him and one of the gates of hell will be closed to him”.
He also quotes Imam Musa Al-Kadhem (peace be upon him) as saying: “Whoever fasts one day of Rajab fire [of hell] will go away from him equal to distance of one year journey and whoever fasts three days [in Rajab] heaven becomes necessary for him”.
That is why this holy month has a special relation with Imam Al-Hussayn (peace be upon him), and it became a an important occasion to renew the covenant with him (peace be upon him). It is narrated from Imam As-Sadiq (peace be upon him) that one who performs the Zyarat of Imam Al-Hussayn (peace be upon him) on 1st Rajab would be forgiven by Allah." Also It is narrated from Ibn Abi Nasr that he asked Imam Ar-Reda (peace be upon him) what was the best time for the Zyarat of Imam Al-Hussayn (peace be upon him). He (peace be upon him) replied: 15th Rajab and 15th Sha'ban.
The lovers and followers of Ahl Al-Bayt (peace be upon them) have the habit to welcome the holy month of Rajab at the shrines of the Master of martyrs and his brother Aba Al-Fadl Al-Abbas (peace be upon both of them) following the recommendations of the holy imams during this holy month, which beginning marks the birth anniversaries of Imam Al-Baqer and Imam Al-Hadi (peace be upon both of them).
Both holy shrines of Imam Al-Hussayn and Al-Abbas (peace be upon both of them), the courtyard between the two holy shrines and the road leading to them were filled with the crowds of visitors coming from different provinces of Iraq as well as those coming from Arab countries and the foreigners all of them coming to perform the Zyarat of Imam Al-Hussayn and his brother Aba Al-Fadl Al-Abbas (peace be upon both of them) in the first of the blessed month of Rajab.