Sahih Muslim 817 a
The Book of Prayer - Travellers
The virtue of one who acts in accordance with the Qur’an and teaches it. And the virtue of one who learns wisdom from Fiqh or other types of knowledge, then acts upon it and teaches it
'Amir b. Wathila reported that Nafi' b. 'Abd al-Harith met 'Umar at 'Usfan and 'Umar had employed him as collector in Mecca. 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 Prophet (ﷺ) said: By this Book, Allah would exalt some peoples and degrade others.