The Holy Prophet (S.A.W.) said:
Surely, there exists in the hearts of the Mu'mineen, with respect to the martyrdom of Husain (A.S.), a heat that never subsides.

Mustadrak al‑Wasail vol 10 pg. 318

Imam Redha (A.S.) said:
The one for whom the day of A'ashura is a day of tragedy, grief and weeping, Allah The Mighty, The Glorious, shall make the Day of Judgment, a day of joy and happiness for him.

Bihar al‑Anwar, vol. 44, pg. 284

Imam Redha (A.S.) said:
With the advent of the month of Muharram, my father Imam Kadhim (A.S.) would never be seen laughing; gloom and sadness would overcome him for (the first) ten days of the month; and when the tenth day of the month would dawn, it would be a day of tragedy, grief and weeping for him.

Amaali Saduq, pg. 111

The Holy Prophet (S.A.W.) said:
O' Fatimah! Every eye shall be weeping on the Day of Judgment except the eye which has shed tears over the tragedy of Husain (A.S.) for surely, that eye shall be laughing and shall be given the glad tidings of the bounties and comforts of Paradise.

Bihar al‑Anwar, vol. 44 pg. 193.