Imām Alī ibn Mūsā al-Rezā (A.S.) said:



“Whoever avoids attending to his worldly affairs on the tenth of Muharram, Allāh will fulfill all the wishes and desires of this world as well as the hereafter. Whoever considers this day to be a day of mourning, sorrow and weeping for himself, Allāh the Glorified will make the day of Qiyāmah to be a day of rejoicing for him and his eyes will be cooled in Paradise on account of us. And whoever considers the tenth of Muharram to be a day of prosperity and buys something for his house (considering it a good omen), then Allāh will not give him affluence in that thing. And on the day of Qiyāmah he will be made to arise along with Yazid, Ubaydullāh bin Ziyād and Umar ibn Sa’ad (may Allāh’s curse be on all of them) and will be thrown into the lowest abyss of hell..”



[Reference: Nafasul Mahmum, Section 2, Hadith 16]