The Earnings of the Teacher
A brief essay showing that the earnings one makes from teaching the Qurʾān is from the best forms of attaining sustenance.
My people know that my profession was not capable of providing substance to my family. And as I will be busy serving the Muslim nation, my family will eat from the National Treasury of Muslims, and I will practice the profession of serving the Muslims.
This topic was also discussed in the third book along with its proofs. It is appropriate for him to teach without taking wages if he is self-sufficient. If he is in need, then his salary is from the Bayt al- Māl because teaching is part of the general benefit to the Muslim public. If it was difficult to get money from the Bayt al- Māl, and the people in his district or village agree to give him a salary, then that is permissible. It is also permissible to receive money for teaching someone.
The proofs for all these are:
1) It is more appropriate to teach voluntarily, without a salary.
a) Conveyance of knowledge is an Islamic duty like Salah and fasting. Allāh said,
"(And remember) when Allāh took a covenant from those who were given the Scripture (Jews and Christians) to make it ( the news of the coming of Prophet Muḥammad and the religious knowledge) known and clear to mankind, and not o hide it, but they threw it away behind their backs, and purchased with it some miserable gain! And indeed worst is that which they bought."
(Sūrah Āl ʿImrān 3:187)
Therefore, he does not deserve a salary because it is obligatory on him.
This tafsīr is in Qurṭabī (1/185).
b) Taking the example of the Prophet (ṣallallāhu ʿalayhi wa-sallam).
"He should follow the example of the Prophet (ṣallallāhu ʿalayhi wa-sallam) by not taking a reward for anything he teaches the people. He should not expect compensation or gratitude, but he should teach for the sake of Allāh and to draw nearer to Him. He should not perceive that he is doing a favour to them, even though gratitude on their part is a must. On the contrary, he should notice their virtue of purifying their hearts to draw nearer to Allāh and allowing him to plant his knowledge there. Just like the one who loans you his land to cultivate. The benefit you receive from his land is more than his. So how do you burden him for a favour when your reward with Allāh is more than the students' reward? If it was not for the students' learning, he would not receive this reward. So do not ask for a reward except from Allāh.
"And O my people! I ask of you no wealth for it, my reward is from none but Allāh."
(Sūrah Hūd 11:29)" 
2) He should take a grant from the Bayt al- Māl if needed. Because he is doing a duty to the Muslims which is fardh kifāyah (obligatory upon the Muslims as a whole), his sustenance comes from the Bayt al- Māl.
Al-Baghdādī said, "It's the Imām's duty to allot certain wages from the Bayt al- Māl for the ones who teach and gives fatwá́, so they can focus their time on teaching, instead of earning a living." 
The proof for that is that the Companions (raḍī Allāhu ʿʿʿanhum) did it with Abū Bakr when he was Caliph.
Narrated 'Āʿishah, When Abū Bakr was chosen Caliph, he said,
"My people know that my profession was not capable of providing substance to my family. And as I will be busy serving the Muslim nation, my family will eat from the National Treasury of Muslims, and I will practice the profession of serving the Muslims."
Ibn Ḥajar said,
"The designated amount was agreed upon by the Companions."
Ibn Sa'ad narrated with a mursal isnād, whose men were of reliable character:
"When Abū Bakr was made Caliph he went to the market with some thawbs to make business. ʿUmar and Abū ʿʿUbaydah saw him with the goods. They said: 'You're doing that and you're the Leader of the Muslims?' He said; ' How can I feed my family?' They said; 'We will assign to you half a sheep for each day."
3) If there is no Bayt al- Māl, and he is in need, he should take a fī from the village-people or from his student.
Narrated Ibn ʿAbbās from the Prophet (ṣallallāhu ʿalayhi wa-sallam),
"It is perfectly legal to charge for Allāh's Book." (Qurʾān).
Ibn Ḥajar said,
"The majority of the scholars use this Ḥadīth to support taking a salary for teaching The Qurʾān. The Ḥanafīs contest that. They say it is not allowed to charge for teaching but it is allowed for healing by Ruqyah. They also say teaching the Qurʾān is an act of worship, and the reward for worship is from Allāh."
Hanafis also have more proofs for their ruling. Of it, is this statement and all others with the same meaning:
"And believe in what I have sent down (this Qurʾān), confirming that which is with you, (the Torah and the Gospel), and be not the first to disbelieve therein, and buy not with My Verses (the Torah and the Gospel) a small price, and fear Me and Me Alone."
(Sūrah al-Baqarah 2:41)
They also used a lot of weak aḥādīth to support their views. Qurṭabī mentioned the weak aḥādīth that they use in his tafsīr. Refer to it if you wish.
Ibn Taymīyyah said,
"The scholars of Islām have a disagreement on the issue of taking recompense for the Qurʾān. There are three different opinions…the most correct one is that itis permissible for the one in need." 
If this ruling, charging for teaching the Qurʾān, is established, then it is also permissible to receive wages for teaching other Islamic studies.
 Tafsīr al- Qurṭabī (1/185)
 al-Ghazzālī, Iḥyā 'ʿUlūm al-Dīn (1/70)
 Al-Khatīb Al-Baghdādī, al-Faqīḥ wal-Mutafaqqih (2/164)
 Related by Bukhārī (3/284)
 Ibn Ḥajar, Fat′h al-Bārī (4/305)
 Related by Bukhārī (3/263)
 Ibn Ḥajar, Fat′h al-Bārī (4/453)
 Tafsīr al- Qurṭabī (1/355)
 Ibn Taymīyyah, Majmūʿ al-Fatāwá ( 30/192)