'Amir bin Wathila reported that Nafi' bin 'Abdul Harith met 'Umar at 'Usfan and 'Umar had employed him as collector in Makkah. He (Hadrat 'Umar) said to him (Nafi'): Whom have you appointed as collector over the people of the valley? He said: Ibn Abza. He said: Who is Ibn Abza? He said: He is one of our freed slaves. He (Hadrat 'Umar) said: So you have appointed a freed slave over them. He said: He is well versed In the Book of Allah. the Exalted and Great, and he is well versed In the commandments and injunctions (of the Shari'ah). 'Umar said: So the Holy Prophet ( صلی اللہ علیہ وسلم ) said: By this Book, Allah would exalt some peoples and degrade others.