Whoever fasts one day from the beginning, middle or end of the month of Rajab

Imam Baqir (a.s) said:

Whoever fasts one day from the beginning, middle or end of the month of Rajab, God will make Paradise obligatory upon him and will place him in our position on the Day of Judgment, and whoever fasts two days of this month, he will be told: You can start again because all your past sins have been forgiven

jami ahadith al-shia,vol9-p436