Knowledge is a tree and action is its fruit.
I advice you O seeker of knowledge to have a sincere and pure intention in your search for knowledge, and that you exert yourself in acting upon what it mandates (from action). This is since knowledge is a tree and action is its fruit. And one can never be considered knowledgeable so long as he doesn’t act upon what he knows.
So do not feel satisfied with actions so long as you are lacking in knowledge, nor feel satisfied with knowledge so long as you fall short in producing actions. Rather, combine between them both, even if your share two is small. So a little of this (knowledge) along with a little of that (action) is what is lost likely to save you in the end, when Allaah bestows His mercy upon His servant and completes His favour upon him.
Knowledge leads to action, just as action leads to salvation. So if the action falls short of the knowledge, then the knowledge becomes a burden upon the one who possesses it. And we seek refuge in Allaah from knowledge that turns into a burden, brings about humiliation, and becomes a shackle on the neck of the one who possesses it.
[An excerpt to the treatise Knowledge Mandates Action by Imaam Abu Bakr Ahmad bin ‘Alee Al-Khateeb Al-Baghdaadee.]