It is related in numerous traditions….

“Do not avoid visiting the grave of Imam Husayn (a.s.) even during the days of prohibition. And one who visits him (his grave) in fear (of the enemies). Allah will give him refuge from the great fear of Qiyamah and he will gain reward proportionate to the fear. And the one who fears due to their fear, Allah will bestow him a refuge under the shade of His empyrean while he shall remain along with Imam Husayn (a.s.) and shall be protected from the fear of the day of Qiyamah”.