(And when thou bringest not a verse for them) i.e. the people of Mecca, as they request (they say: Why hast thou not chosen it?) why not take it upon yourself to bring it from Allah?; It is also said that this means: why do you not invent it yourself? (Say) to them, O Muhammad: (I follow only that which is inspired in me from my Lord) I do and say only that which is revealed to me from my Lord. (This) Qur'an (is insight) an exposition (from your Lord) detailing commands and prohibitions, (and a guidance) and a guidance from error (and a mercy) preventing from punishment (for a people that believe) in the Qur'an.