What they responded with at his saying: 'Indeed, I am the Messenger of the Lord of the worlds' is omitted. This is indicated by his saying: 'So when he came to them with Our signs,' while they were demanding him to bring forth evidence for his claim and to present the sign, they were laughing at it, meaning they were mocking it and ridiculing it, calling it magic. And 'if' is for surprise. If you say: How is it permissible for 'if' of surprise to respond to 'when'? I say: Because the action of surprise is implied with it. It is the factor of the accusative. [Mahamud said: 'It is permissible for a response to 'when' to be with 'if' of surprise because the action of surprise is implied with it, and it is the factor in the accusative... etc.' Ahmad said: The apparent justification for this expression - and Allah knows best - is that each one of these signs, when you contemplate it individually, overwhelms the mind with its greatness, to the extent that one is certain it is the ultimate, and that every sign below it is lesser. When the thought is transferred to its sister, it also encompasses the mind with its greatness, and one becomes oblivious to the first, thus concluding that this is the ultimate, and that every sign below it is lesser. The result is that the mind cannot comprehend both of these signs together, to ascertain the superior from the inferior, but whenever it contemplates one with disbelief, it concludes that it is the ultimate. And on this estimation, all that comes from similar examples applies, and Allah knows best.] In its place, as if it were said: So when he came to them with Our signs, they were surprised at the time of their laughter.