Prophets are under the protection of the Almighty God. None can recognize them until God makes them manifest...
It is narrated that King Mahmood arrested a ruler and took him with him. After living with the king for a while, the ruler embraced Islam after comparing Islam with his religion.
The ruler lived in a separate tent. One day the ruler was sitting crying in his tent that Mahmood passed by and heard him crying and entered the tent. King Mahmood inquired whether he was missing his homeland and if so, he would send him back as the ruler of that land.
The ruler replied, ‘I do not desire the world at the moment. I am thinking how will I face the question on the Day of Judgment as to what kind of a Muslim am I that I did not embrace Islam till Mahmood attacked and brought me with him. How fortunate would it have been had I understood early on that Islam was the true religion?’
(Malfuzat, Vol. 5, p. 404–405)