Al-Husayn ibn Muhammad has narrated from Mu‘alla ibn Muhammad from al-Washa’ from al-Muthanna al-Hannat from al-Qutayba al-A'sha from Ibn Abi Ya‘fur from a slave of Banu Shayban that Abu Ja‘far (al-Baqir)  said: 

إِذَا قَامَ قَائِمُنَا وَضَعَ الله يَدَهُ عَلَى رُءُوسِ الْعِبَادِ فَجَمَعَ بِهَا عُقُولَهُمْ وَكَمَلَتْ بِهِ أَحْلامُهُمْ.

"When our Qa’im (Imam al-Mahdi) rises, Allah will place His hand over the heads of His servants and He will place their intelligence together and complete their understanding.”

Al-Kāfi, v.1