"And if We had made him an angel, We would have made him a man," meaning: We would have placed that angel in the form of a human. "And We would have obscured for them that which they obscure," meaning: and We would have confused for them that which they confuse; because they demanded that an angel be with a human.
Muhammad said: It is also said that the meaning is: We would have caused them to stray by means of that which they strayed by before the angel was sent.