The worship of the ignorant person does not amount to anything; indeed, he is in total corruption and total darkness. Knowledge is also useless without practice, and practice is useless without sincerity (ikhlas). All practice without sincerity is useless, and is not accepted of the practitioner. If you have knowledge and do not put it into practice, that knowledge will be evidence against you. The Prophet s.a.w is reported as having said: "The ignorant person will be punished once, and the learned person seven times."
Why does the ignorant man not learn? Why does the learned man not put his knowledge into practice? You must learn and practise and teach, for this will give you all good things combined. When you hear a word of knowledge, put it into practice and teach it to someone else, you have two rewards: the reward for knowledge and the reward for the sharing of knowledge. The world is darkness and knowledge is a light within it, so he who has no knowledge is blundering about in this darkness and doing more harm than good.
Note: Extracts from lectures given by Shaykh Abdul Qadir al-Jilani in Ramadhan 545 A.H. Reference: The Sublime Revelation (Al-fath ar-Rabbani) Translated from the Arabic by Muhtar Holland.