Narrated Jabir
A bedouin came to the Prophet (ﷺ) and gave a pledge of allegiance for embracing Islam. The next day he came with fever and said (to the Prophet (ﷺ) ), "Please cancel my pledge (of embracing Islam and of emigrating to Medina)." The Prophet (ﷺ) refused (that request) three times and said, "Medina is like a furnace, it expels out the impurities (bad persons) and selects the good ones and makes them perfect."
Narrated Zaid bin Thabit
When the Prophet (ﷺ) went out for (the battle of) Uhud, some of his companions (hypocrites) returned (home). A party of the believers remarked that they would kill those (hypocrites) who had returned, but another party said that they would not kill them. So, this Divine Inspiration was revealed: "Then what is the matter with you that you are divided into two parties concerning the hypocrites." (4.88) The Prophet (ﷺ) said, "Medina expels the bad persons from it, as fire expels the impurities of iron."
Narrated Anas
The Prophet (ﷺ) said, "O Allah! Bestow on Medina twice the blessings You bestowed on Mecca."
Narrated Anas
Whenever the Prophet (ﷺ) returned from a journey and observed the walls of Medina, he would make his Mount go fast, and if he was on an animal (i.e. a horse), he would make it gallop because of his love for Medina.