It is transmitted that the Promised Mahdi (May blessings of Allah and peace be upon him) said that:

"Why do you go to a place where the need for offering prayers following a Rejecter (Munkir) arises."

Naqliyat-e-Mian Abdur Rasheed RZA.

There is another Naqal e Mubarak of Mehdi AS quoted by Hz Bandagi Miyan Shah-e-Khundmir Siddiq-e-Vilayat.

It says "Mana kardan az namaz ba dummbal e munkiran, sahvan guzarda bashed baaz be gardani"

There may be a few errors in persian that I wrote!!! But the meaning of the Naqal is that Mehdi AS prohibited us from offering prayers behind the nonebelievers, if offered unknowingly then repeat the prayer!!!