'If' is combined with 'no' and 'not' for two meanings: the meaning of the prevention of something due to the existence of another, and the meaning of urging. As for 'whether', it is only combined with 'no' alone for urging. Ibn Maqbil said: 'If it were not for modesty and if it were not for religion, I would have criticized you with some of what is in you when you criticized me for my flaw.' [From Ibn Maqbil, and 'if not' and 'if' are originally 'if' which indicates the prevention of something due to the prevention of another, so it is combined with 'no' and 'not', which are negating. Thus, it indicates the prevention of something due to the existence of another, because the negation of negation is affirmation. If it does not have a response, it indicates urging with them in the present tense, and in other cases, it indicates reproach or rebuke. He says: 'If modesty were present, and if religion were present, I would have criticized you with some of the flaws in you, because you criticized me for my flaw.' ] And the meaning is: 'Would that you bring us the angels to witness your truthfulness and support you in your warning,' as His saying, 'If only an angel were sent down to him to be with him as a warner.' Or: 'Would that you bring us the angels for punishment for our denial of you if you are truthful, as the nations that denied their messengers were visited?'