Abud-Darda reported:

The Messenger of Allah (May Allah bless him and grant him peace) said, "He who follows a path in quest of knowledge, Allah will make the path of Jannah easy to him. The angels lower their wings over the seeker of knowledge, being pleased with what he does. The inhabitants of the heavens and the earth and even the fish in the depth of the oceans seek forgiveness for him. The superiority of the learned man over the devout worshipper is like that of the full moon to the rest of the stars (i.e., in brightness). The learned are the heirs of the Prophets who bequeath neither dinar nor dirham but only that of knowledge; and he who acquires it, has in fact acquired an abundant portion."

Narrated Kathir ibn Qays:

 Kathir ibn Qays said: I was sitting with Abu Darda in the mosque of Damascus.

A man came to him and said: Abu Darda, I have come to you from the town of the Messenger of Allah (May Allah bless him and grant him peace) for a tradition that I have heard you relate from the Messenger of Allah (May Allah bless him and grant him peace). I have come for no other purpose.

He said: I heard the Messenger of Allah (May Allah bless him and grant him peace) say: If anyone travels on a road in search of knowledge, Allah will cause him to travel on one of the roads of Paradise. The angels will lower their wings in their great pleasure with one who seeks knowledge, the inhabitants of the heavens and the Earth and the fish in the deep waters will ask forgiveness for the learned man. The superiority of the learned man over the devout is like that of the moon, on the night when it is full, over the rest of the stars. The learned are the heirs of the Prophets, and the Prophets leave neither dinar nor dirham, leaving only knowledge, and he who takes it takes an abundant portion.

It is obligatory to learn the rulings on buying and selling for businessmen, so that they can avoid dubious transactions and transactions involving improper elements in all their dealings. The same applies to people in all professions, and everyone who is involved in a thing must learn the rulings connected to it, so that he can avoid falling into haram when engaging in his profession.