(And they swear a solemn oath) an utmost oath, for when one swears by Allah, one swears a solemn oath (by Allah that if there come unto them a portent) as they have asked (they will believe therein) they will believe in that sign. (Say) O Muhammad, to those who sneer and their folk: (Portents are with Allah) the signs come from Allah (and (so is) that which telleth you) and how do you know, O believers (that if such) the signs (came unto them they would not believe) by Allah they will not believe in the sign.