Yes, it is permissible; because this reward is in exchange for dedicating time to this task. Abu Sa'id Al-Khudri (may Allah be pleased with him) narrated that he recited the opening of the Book (Al-Fatiha) and took a flock of sheep, dividing it among himself and his companions by the command of the Prophet (peace be upon him), who said: "The most rightful thing you can take a reward for is the Book of Allah," as mentioned in Sahih Al-Bukhari 2: 795. See: Al-Bada'i 1: 149-152, and the preference for hiring for teaching the Quran, p. 227, Al-Muheet p. 151, and Radd Al-Muhtar 5: 34-35.