67: Say, "It is a great tiding."

Say (the command is repeated to signify that what is being said is a momentous matter of grave significance, which must be attended to with concern, both in command and in compliance).

It is (i.e., that which I have informed you of: my being a warner-messenger, and that Allah—Exalted is He—is One, having no partner).

A great tiding (a report of immense benefit, in which there is absolutely no doubt).