The basis in quest for knowledge is that it should be via taking instructions from and meeting the teachers, doing Al-Muthaafanah to them (that is, being under their tutelage) and taking knowledge from their tongues not from scrolls or pages of books (alone). The former is similar to taking what belongs to one from one's relation who can talk, and that is the teacher. The latter is taking (knowledge) from books whcih are inanimate things (that cannot talk); therefore, how can there be a tying of kinship?
It has been said: 'Whoever enters into knowledge alone will come out of it alone.'
[Al-Jawaahir Wa Ad-Durar of As-Sakhaawi 1/58].
That is, whoever goes in quest of knowledge alone without a Shaykh will come out of it without (any) knowledge. (The Islamic) knowledge is a field and every field depends on its experts therefore the field (of Islamic Knowledge) must be learnt from its experts.
That knowledge should be sought directly from scholars seems to be the consensus of the people of knowledge except those who dissented like Aliyy bn Ridwaan Al-Misree (who died year 453 Hijrah). The scholars of his time, and those who came after them, refuted him on his stance. Al-Haafidh Adh-Dhahabi (rahima-hu Allaah) said in the biography of Aliyy bn Ridwaan:
'He had no Shaykh rather he busied himself with taking from books (alone); he even wrote a book saying knowledge can be acquired from books (alone) and that (taking knowledge from) books is more effective than taking from teachers. This is an error (from him).'
End of quote. [Siyar A'laamin-Nubalaa, 18/105].
(Al-Imam) As-Safadiyy had really refuted him crushingly in his book, Al-Waafee, so also was Az-Zabeeydee in Shar'h Al-Ihyaa quoting from a number of scholars coming up with a number of reasons that the opinion of Alee bn Ridwaan was faulty. Among those was what Ibn But'laan said in his refutation of Alee:
'The sixth point: Many things that dissuade from knowledge are found in books and these things are worthless in the sight of teachers; these are alterations that crop up in the face of similar letters while how to pronounce them is not stated, and that can be due to impatience of the sight, little experience with respect to the Arabic Grammar, or corrupting what is found in the book, or trying to correct the book, writing down what is not read, or reading what is not written, also the school-of-thought of the author (of the book one is reading), the sickly way it is reproduced and copied, reader merging what is not supposed to be merged, an act of mix-up from a beginner, mention of technical terms in the field (in question), so also are Greek terms which the writer retains in its original form like the word: An-Nuurus.
All the above do have negative consequence on knowledge. A learner will feel the ease when he has rested all those responsibilities on a (qualified) teacher.
Therefore if the affair is like this, thus learning from scholars is better and worthier than when a person reads by himself. This is what we are trying to explain…
This is the reason scholars do say:
'Do not take knowledge from a Suhufee or a Mus'hafee.'
That is: Do not learn the Qur'ân from a person who learns the Qur'ân from (reading) the Mus'haf (alone) or hadith or other aspects of the Islamic Knowledge from a person who takes them from scrolls… '
End of quote. [Shar'h Al-Ihyaa, 1/66].
The final and crushing evidence to the opinion of Ibn Ridwaan is that you will see thousands of biographies and life-histories over different epochs and over different generations such that all those will be filled with names of teachers and students – those whom had little and much (of both teachers in one hand and students on the other hand). See a fragment of those who had much from teachers such that their number got to thousands as it has come in Al-Uzaab Min Al-Isfaar of its author.
Abu Hayyan Muhammad Yusuf Al-Andalusee (d. 745) used to say whenever Ibn Maalik (the famous grammarian) was mentioned beside him that:
'Who are his teachers?'
[Muqaddimah of the Tahqiq on Qaadi Iyaad's book, Al-Ghunyah, p. 16 - 17].
Al-Waleed said: Al-Auzaaee used to say:
'This knowledge of Islam was once honourable; men used to acquire it from one another. But when it went into books, those who were not qualified came into it.'
Ibn Al-Mubaarak reported the like of that from Al-Auzaaee:
'There is no doubt that taking knowledge from scrolls (alone) and with authorization makes one prone to errors most especially in that generation when books were not dotted and vowelized thus it was possible that words could be misinterpreted in a way that its meaning would be regarded as abnormal while the like of that could not have occurred if the knowledge had been acquired from the lips of men (that is, scholars). So also was narrating from memory could have brought illusions unlike narrating from a well-checked book (under a teacher).'
End of quote. [Siyar, 7/114].
Ibn Khaldun had a splendid research work on the matter as it has come in his Al-Muqaddimah.
One of the scholars has said:
'Whoever has not talked mouth-to-mouth with a scholar with regard to his foundations, his certainty is amid troubling thoughts.'
Abu Hayyan used to chant these lines of poetry:
The unskilled one thinks that books (alone) guide
That they are brotherly to acquisition of knowledge
The ignoramus does not know that books contain
Hazy things that often confound the dexterous ones
When you approach knowledge without a teacher
You will be astray from the straight path
The matters will become confusing to you such that
You will be more astray than Tauma Al-Hakim.
Translated from Shaykh Bakr Abu Zayd's Hilyah Taalib Ilm with its Shar'h by Shaykh Al-Uthaymeen; p. 82-85.