Source: Sheikh Saaleh al-Fauzaan
Knowledge is of two categories: beneficial knowledge and harmful knowledge.
Beneficial knowledge is itself divided into two categories.
First is that knowledge which is tremendous in its benefit, as it benefits in this world and continuing to benefit in the Hereafter. This is religious Sharee’ah knowledge.
Second, that which is limited and restricted to matters related to the life of this world, such as learning the process manufacturing goods. It is a type of knowledge related to specifically to worldly affairs.
And Sharee’ah knowledge is further divided into two types:
Firstly, knowledge of how to worship Allaah alone without associating anything with Him in that worship, which is the foundation.
Secondly, the knowledge which springs or comes from this foundation, and it is the correct understanding of how to implement and practice the religion and everything related to it.
As for harmful knowledge, these are subjects such as knowledge of magic and of astrology, which is knowledge of prediction of the future and fortunes. Sheikh al-Islaam Ibn Taymeeyah mentioned that Yahya ibn Umair stated:
“The branches of knowledge are five:
First is that knowledge which is the life of the religion, this is the knowledge of tawheed, meaning the worship of Allaah Alone without associates or partners. Secondly, there is that knowledge which nourishes the religion, this is the knowledge of reminding one of the meanings and the understanding of the Qur’aan and hadeeth narrations. Third, there is that knowledge which is a medicine and healing for the religion, this is the knowledge of rulings such that when situations come upon the worshipper as he will need to turn to one who will help and resolve that situation for him, as was said by Ibn Masood, “There is that knowledge which is a healing and cure for this religion and that is the knowledge of transmitted and preserved statements; and there is knowledge in which there is the destruction of the religion and that is the knowledge of magic and what is similar to it….” 1