(And when it is said unto them) i.e. to Jews, (believe) in Muhammad (pbuh) (as the people believe), i.e. 'Abdullah Ibn Salam and his companions, (they say: Shall we believe) in Muhammad (pbuh) and the Qur'an, (as the foolish believe?), i.e. as the stupid and ignorant do, (Surely they are the fools) the stupid and ignorant. (But they know not) that they are so.