In The Name of Allaah, The Most Merciful, The Bestower of Mercy

The likeness of those who were entrusted with the [obligation of the] Taurat, but who subsequently failed in those [obligations], is as the likeness of a donkey who carries huge burdens of books [but understands nothing from them]. How bad is the example [or the likeness] of people who deny the Ayaat [proofs, evidences, verses, signs, revelations, etc.] of Allah. And Allah guides not the people who are wrong-doers.

[Surah Al-Jumu’ah’ Aayah 5]

They [i.e. the corrupt scholars amongst Bani Israa’eel] abandoned acting upon the knowledge that was revealed to Moosaa [alayhis salaam], so Allaah likened them to a donkey carrying huge burdens of books. A donkey cannot distinguish whether something good or evil is on top of it – does not know whether it is carrying a living thing or books. Likewise, this is the likeness of the one who does not act.

It is incumbent upon us to establish the Salaah, give Zakaat, fast during the month of Ramadhaan and perform hajj [i.e. hajj obligated on those who can afford it] in the manner legislated by Allaah [i.e. based on the evidences found in Qur’aan and the authentic Sunnah of the Messenger (sallal laahu alayhi wasallam), and not based on innovations in religion].

It is incumbent upon us to [hold onto] the sound creed in the manner Allaah legislated it for us; keeping away from Shirk, Bidah and all types of disobedience to Allaah. We should act upon what Allaah has taught us [i.e. knowledge found in the Qur’aan and authentic Sunnah as understood by the Sahaabah].

We should believe in the sound creed, and [we should] fight against Shirk and all types of bidah [i.e. teach Tawheed, the authentic Sunnah and the path of the Sahaabah, and refute Shirk and Bidah], enjoin good and forbid evil. This is all considered to be part of acting upon [knowledge after acquiring it].

Your knowledge decreases depending on your shortcomings in any affair, and the rebuke a person receives will depend on [how much he has] abandoned that which Allaah has taught him [i.e. the knowledge he has acquired from the Qur’aan and the authentic Sunnah as understood by the Sahaabah].

Source: Marhaban Yaa Taalibal Ilm. page 226-227. slightly paraphrased