Rafidi Abdulhusayn al-Neysaburi in his book “Taqwimu shia” discussed and mentioned day when was assassinated Umar ibn Khattab (r.a).
Under the heading “Death of Umar ibn Khattab”, he said:
And this is day of rejoice for Ahlalbayt, more this is day of rejoice for messengers, angels, inhabitants of two gardens, and lovers of commander of faithful (a.s) and his pure children, because in it was answered the prayer of oppressed mistress Fatimah az-Zahra (a.s). And this is great day, and great holiday. And prophet (sallalahu alaihi wa ali) gave an order for people to take it as holiday, and mentioned for it some deeds. And Allah would forgive the one who would gave charity in this day. And it is desirable in it to feed brothers, wear new clothes and distribute perfume, and thank Allah and worship Him. And it is desirable to make gusl in this day.
And for this day mentioned merits and names, amongst them: THE GREATEST HOLIDAY OF ALLAH, second Ghadir, Second Fitr, day of rejoice of shias, the holiday of Ahlalbayt, THE DAY OF DEATH OF HYPOCRISY, day of acceptance of deeds, day of victory of oppressed…..