Imam Mahdi (a.t.f.s.) to Ali b. Mahziyaar – …and I will go towards Yathrib (Medina) and destroy al-Hujrah and evict those in it and those two (Abu Bakr and Umar l.a.) while they are fresh and order that they be hanged towards Baqee and order the two dried branches of their crucifixion to sprout leaves from below and people will be examined through them in a way more severe than before and a caller will call out as an examination – O sky leave (him) and O earth take (him). Then on that day, none shall remain on the face of the earth except a believer who has been purified.

Behaar al-Anwaar v 53 p 104 from Al-Khesaal