Question: Is it allowed for a person to teach any book and he did not study and learn at the hand of a Shaikh. He only takes from the books translated into the English language and depending on that he teaches this book to the people. So is this allowed?
Answer: The one who plunges himself in what he is not proficient in teaching or other than that, harms himself and others more than he benefits. Allah ‘azz wa jall says:
قُلْ مَا أَسْأَلُكُمْ عَلَيْهِ مِنْ أَجْرٍ وَمَا أَنَا مِنَ المُتَكَلِّفِينَ
Say (O Muhammad SAW): “No wage do I ask of you for this (the Quran), nor am I one of the Mutakallifun (those who pretend and fabricate things which do not exist).
And Allah says:
وَلا تَقْفُ مَا لَيْسَ لَكَ بِهِ عِلْمٌ إِنَّ السَّمْعَ وَالْبَصَرَ وَالْفُؤَادَ كُلُّ أُوْلَئِكَ كَانَ عَنْهُ مَسْئُولًا
And follow not (O man i.e., say not, or do not or witness not, etc.) that of which you have no knowledge
And Allah says:
قُلْ إِنَّمَا حَرَّمَ رَبِّيَ الْفَوَاحِشَ مَا ظَهَرَ مِنْهَا وَمَا بَطَنَ وَالإِثْمَ وَالْبَغْيَ بِغَيْرِ الْحَقِّ وَأَنْ تُشْرِكُوا بِاللهِ مَا لَمْ يُنَزِّلْ بِهِ سُلْطَانًا وَأَنْ تَقُولُوا عَلَى اللهِ مَا لا تَعْلَمُونَ
Say (O Muhammad SAW): “(But) the things that my Lord has indeed forbidden are Al-Fawahish (great evil sins, every kind of unlawful sexual intercourse, etc.) whether committed openly or secretly, sins (of all kinds), unrighteous oppression, joining partners (in worship) with Allah for which He has given no authority, and saying things about Allah of which you have no knowledge.
As for the one who is capable of understanding knowledge by his effort and obtaining it from within the books, so it is upon him to teach it. It is not required that he does not teach except a book he studied with a teacher.
[ Taken from: http://www.sh-yahia.net/show_books_40.html ]
Translated by Faisal ibn Abdul Qaadir ibn Hassan