Bismillah
hir-Rahman nir-Rahim
Hadith:
Madiney ki misaal bhatti
ki si hai mail-kuchail (impurities) ko dur karkey khalis johar ko nikhar deti
hai
Jabir Radiallahu anhu se
riyat ghai ki ek aarabi Rasoollallahu Sallallahu Alaihi Wasallam ki khidmat
mein hazir hokar islam par bait ki, dusrey din aaya to usey bukhar tha kahney laga ki meri bait ko tod dijiye 3
baar usney yahi kaha Aap Sallallahu Alaihi Wasallam ne inkaar kiya aur farmaya
ki madiney ki misaal bhatti ki si hai mail-kuchail (impurities) ko dur karkey
khalis johar ko nikhar deti hai.Sahih Bukhari, Vol 3, 1874
Narrated Jabir Radiallahu anhu : A bedouin came to the Prophet Sallallahu Alaihi Wasallam and gave a pledge of allegiance for embracing Islam. The next day he came with fever and said "Please cancel my pledge (of embracing Islam and of emigrating to Medina)." Three times he said , The Prophet Sallallahu Alaihi Wasallam refused (that request) and said, "Medina is like a furnace, it expels out the impurities (bad persons) and selects the good ones and makes them perfect
Sahih Bukhari, Vol 3, Book 30, No. 107: