Seeking legislative knowledge is Fard Kifaayah, if a sufficient number of people carry it out (i.e. the obligation), it becomes a Sunnah for the remainder (of people). Seeking knowledge may become a specific obligation (upon someone) i.e. Fard ‘Ayn. Its guideline is obtaining knowledge of the act of worship that one desires to practice or an interaction (Mu’aamalah) that one wishes to carry out. In this instance, it is obligatory upon him that he knows how to worship Allaah and how to carry out this interaction (Mu’aamalah).
All knowledge besides this is Fard Kifaayah. It is important that the student of knowledge recognizes that he is upholding a Fard Kifaayah during his quest so that he may be rewarded for carrying out an obligation while obtaining knowledge. There is no doubt that seeking knowledge is from the most virtuous of actions. Rather it is Jihaad in the Cause of Allaah especially in our time when innovations have begun to become prevalent spreading abundantly in the Islaamic community. An abundance of ignorance has arisen from those giving religious verdicts without knowledge, and many of the people have begun to dispute and quarrel. So these three affairs make it a duty upon the youth to be concerned with seeking knowledge.
Firstly: The evils of innovations have become prevalent.
Secondly: The people give religious verdicts without knowledge.
Thirdly: There is much dispute about issues that may be clear to the people of knowledge, but they have begun to argue about them without knowledge.
So due to this, we are in need of people possessing knowledge that are firmly grounded (in that knowledge), have a wide scope in their reading, possess understanding of Allaah’s religion, and have wisdom in directing the servants of Allaah since many of the people ascertain speculative knowledge in an issue and they do not care about correcting the people and cultivating them. When they give a verdict of this or that, it becomes a means to a greater evil that none knows the extent of it save Allaah.
Source: Kitaabul ‘Ilm