17. That servant of God, in this one sentence, put together all the arguments required for determining the genuineness of Prophethood. The genuineness of a Prophet can be determined by two things. First, his word and deed; second, his being selfless. What the person meant to say was this: First, whatever these people are saying is perfectly reasonable, and their own character also is pure; second, no one can prove that they are calling the people to this faith on account of a selfish motive. Therefore, there is no reason why they should not be listened to. By citing this reasoning of the person the Quran set a criterion before the people of how to judge and determine the genuineness of the Prophethood of a Prophet, as if to say: The word and deed of the Prophet Muhammad (peace be upon him) bear full evidence that he is on the right path. Then, no one can point out any selfish motive or interest behind his struggle of preaching his message. Therefore, there is no reason why a sensible person should reject what he presents.
18. This sentence has two parts. The first part is a masterpiece of reasoning, the second of the wisdom of preaching. In the first part he says: To worship the Creator is the demand of both reason and nature; it would be highly unreasonable that one should worship those who have not created him and should deny to be the servant of Him Who has created him. In the second part he warns his people to the effect: All of you ultimately have to die and return to that God adoption of Whose service you object to. Therefore, you should consider for yourselves as to what goodness you could expect by turning away from Him.