7th and 8th century Ahle Tasannun scholar and traditionalist Ibrahim Hamveeni in his book Faraaed al-Simtain, vol. 2, chapter 35, narrates a tradition that:
فَقَالَ لَهُ أُبَيٌّ وَ مَا دَلاَئِلُهُ وَ عَلاَمَاتُهُ يَا رَسُولَ اَللَّهِ قَالَ لَهُ عَلَمٌ إِذَا حَانَ وَقْتُ خُرُوجِهِ اِنْتَشَرَ ذَلِكَ اَلْعَلَمُ مِنْ نَفْسِهِ وَ أَنْطَقَهُ اَللَّهُ تَبَارَكَ وَ تَعَالَى فَنَادَاهُ اَلْعَلَمُ اُخْرُجْ يَا وَلِيَّ اَللَّهِ فَاقْتُلْ أَعْدَاءَ اَللَّهِ
Imam Husain (peace be upon him) says that Ubay Ibn Kaab asked the Holy Prophet (peace be upon him and his holy progeny), “O Messenger of Allah! What are the signs and indicators of the reappearance of Imam Mahdi (a.t.f.s.)?”
He (peace be upon him and his holy progeny) replied, “He has a flag. When the time of the reappearance will arrive, the flag will unfurl on its own, and Allah, Mighty and Majestic be He, will make the flag speak and it will call out, “Rise, O Vicegerent of Allah and kill the enemies of Allah’.”
“Another sign is that Imam Mahdi (a.t.f.s.) has a sheathed sword. When the time of reappearance will arrive, this sword will unsheath itself on its own. Allah will make the sword (also) speak and it will call out, “Rise, O Vicegerent of Allah and you must fight the enemies of Allah’.”
It is evident from this tradition that the information of the reappearance of Imam Mahdi (a.t.f.s.) will be given through two signs – the flag and the sword, and both will speak up with Divine permission.
Apart from this, in another famous book of the Ahle Tasannun called Yanaabee’ al-Mawaddah by Hafiz Sulaiman Ibn Ibrahim Qunduzi, chapter 71, p. 487, we find a tradition in which Imam Sadiq (a.s.) has spoken about the information of reappearance in the following words:
“Imam Mahdi (a.t.f.s.) will hear a call informing him that the time of his rising has arrived after which he will rise. That day will be very tough for the disbelievers.”
We pray to Allah that He hastens the advent of Imam Mahdi (a.t.f.s.), and rids the world of all disbelief and hypocrisy. May Allah include us with him in this great mission.
Aameen, O Lord of the worlds!