18.56
Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
(We send not the messengers save as bearers of good news) Paradise for the believers (and warners) against hell for the disbelievers. (Those who disbelieve) in the scriptures and messengers (contend with falsehood) with idolatry (in order to refute) to nullify (the Truth) and guidance (thereby. And they take Our revelations) Our scriptures and messengers (and that wherewith they are threatened) of chastisement (as a jest) and mockery.
And We do not send messengers except as bearers of good tidings to believers and as warners as threateners to disbelievers. But those who disbelieve dispute with falsehood when they say that ‘Has God sent a human as a messenger from Him?’ Q. 1794 and the like of such statements that they may refute thereby that by way of their disputing they may invalidate the truth the Qur’ān. And they have taken My signs namely the Qur’ān and that whereof they have been warned in the way of the Fire derisively in mockery.
Allah tells us about the rebellion of the disbelievers in ancient times and in more recent times, and how they rejected the obvious truth even when they witnessed clear signs and proofs. Nothing stopped them from following the truth except their demand to witness with their own eyes the punishment which they were being warned about. As some of them said to their Prophet:
(And they say: "O you to whom the Reminder has been sent down! Verily, you are a mad man! Why do you not bring angels to us if you are of the truthful'') 15:6-7. There are other Ayat refering to the same thing. Then Allah says:
إِلاَّ أَن تَأْتِيَهُمْ سُنَّةُ الاٌّوَّلِينَ
(except that the ways of the ancients be repeated with them,) meaning, their overwhelming punishment, destroying every last one of them.
أَوْ يَأْتِيَهُمُ الْعَذَابُ قُبُلاً
(or the torment be brought to them face to face.) they see it with their own eyes, being directly confronted with it. Then Allah says:
(And We send not the Messengers except as bearers of good news and warners.) before the punishment they give good news to those who believe in them and follow them, and warnings to those who reject them and oppose them. Then Allah tells us about the disbelievers who argue:
بِالْبَـطِلِ لِيُدْحِضُواْ بِهِ الْحَقَّ
(with falsehood, in order to refute the truth thereby.) they try to weaken the truth that the Messengers brought, but they cannot achieve that.
وَاتَّخَذُواْ ءايَاتِى وَمَا أُنْذِرُواْ هُزُواً
(And they take My Ayat and that which they are warned for jest!) they take the proof, evidence and miracles sent with the Messengers to warn them, and make them fear the punishment;
هُزُواً
(as a jest and mockery) and they make fun of them, which is the worst type of disbelief.
18.56
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
This verse has two meanings: (1) We send Our Messengers to forewarn the people before the coming of the judgment of the good results of obedience and the evil consequences of disobedience. But these foolish people are not taking advantage of these forewarnings and insist on seeing the same evil end from which the Messengers desire to save them. (2) It' they insist on meeting with the scourge, they should not demand this from the Messenger because the Messenger is sent not to bring a scourge but to warn the people beforehand to escape from it.