After the evening prayers on Sunday (30 Safar 1442 AH) the holy dome's flag of the shrine of Aba al-Fadl al-Abbas (peace be upon him) was replaced by the red flag embroidered with the phrase (Ya Qamar [O moon of] Bani Hashem), marking the end of the Muhammadian season of sadness in two months Muharram and Safar, and the advent of the month of Rabi’ al-Awal.
It is noteworthy that the red flag remains high above the holy dome for 10 months, and indicates that the owner of the grave was killed but his revenge was not yet taken. In the past, the Arabs used to put a red flag on the grave of he who has been killed and his revenge was not yet taken, and the red flag is removed once the revenge is taken. And up to now, the red flag remains fluttering on top of the domes of the holy shrines of the Master of martyrs and of his brother Aba al-Fadl (peace be upon both of them).
And raising the black flag is to indicate that these days are the days when the owner of this tomb was killed, so we see the black flag is placed on the dome of the shrines of the Master of martyrs; Imam al-Hussayn and of Aba al-Fadl al-Abbas (peace be upon them) only during the days of Muharram and Safar.
O our Master, O Master of the Time, is it not time for you to take revenge for he who was killed in Karbala? Is it not time to remove this red flag from the dome of your grandfather al-Hussayn? When, Master, will we hear the caller calling "O to the revenges of al-Hussayn [Ya li Tharat al-Hussayn]"?