Because Allah, the Exalted, has said: «فاعلم أنه لا إله إلا الله‏» (So know that there is no deity worthy of worship except Allah), thus Allah began with knowledge. And (in the hadith it is mentioned) that the scholars are the heirs of the prophets. (And) the prophets left as inheritance only knowledge. So whoever acquires knowledge has indeed acquired a great share. And whoever treads a path seeking knowledge, Allah makes the path to Paradise easy for him. And Allah, the Exalted, has said that only those of His servants fear Allah who have knowledge. And (in another place) He said: and none comprehend it except the scholars. And He said: and those (disbelievers) said, "If only we had listened or used reason, we would not be among the companions of the Blaze." And He said: Are those who know equal to those who do not know? And the Messenger of Allah (peace and blessings be upon him) said: When Allah intends good for someone, He grants him understanding of the religion. And knowledge is only acquired by learning. And Abu Dharr (may Allah be pleased with him) said: If you were to place the sword here—and he pointed to his neck—and I thought that I could convey even a single word I heard from the Prophet (peace and blessings be upon him) before my neck was struck, I would certainly convey it. And the Prophet (peace and blessings be upon him) said: Let the one who is present convey (my words) to the one who is absent. And Ibn Abbas (may Allah be pleased with them both) said that by the verse «كونوا ربانيين‏» is meant the wise, the jurists, the scholars. And «رباني» refers to the one who educates people in knowledge by explaining minor issues before major ones.

Narrated Ibn Mas`ud: The Prophet used to take care of us in preaching by selecting a suitable time, so that we might not get bored. (He abstained from pestering us with sermons and knowledge all the time).