Сад 38:87

One basic virtue of a preacher is that he does not demand any remuneration from his hearers. Another is that he does not raise any material issues between them and himself. The call of the Quran is the call of the Hereafter. Therefore, if a man, on the one hand, gives the call of the Hereafter and of the Quran and, on the other, runs a campaign for material gain, then he figures as an insincere person. And who will pay attention to the pleadings of a person who has proved himself to be insincere? Similarly, a preacher does not make statements concocted by himself. He simply passes on whatever he has received from God. Masruq Tabi‘i (a contemporary of the Prophet’s Companions) recounts a tradition of ‘Abdullah ibn Mas‘ud who said, ‘O, people! One who knows should talk, and one who does not know should simply say that God knows better. He will seem wise if he states that God knows better (with regard to things which he does not know), because God said to his Prophet, ‘Say, no reward do I ask of you for this, nor am I a pretender.’ (Tafsir ibn Kathir, vol. IV, p. 44 ). Similarly, it is also required of the preacher of truth to present his call in the shape of well-meaning advice. His discourse should be that of a well-wisher and should not be in the nature of debate or polemics.