﴿ وَأَقْسَمُوا۟ بِٱللَّهِ جَهْدَ أَيْمَٰنِهِمْ لَئِن جَآءَهُمْ نَذِيرٌۭ لَّيَكُونُنَّ أَهْدَىٰ مِنْ إِحْدَى ٱلْأُمَمِ ۖ فَلَمَّا جَآءَهُمْ نَذِيرٌۭ مَّا زَادَهُمْ إِلَّا نُفُورًا ﴾

“As it is, they [who are averse to the truth often] swear by God with their most solemn oaths that if a warner should ever come to them, they would follow his guidance better than any of the communities [of old had followed the warner sent to them]: but now that a warner has come unto them, [his call] but increases their aversion,”

(And they swore by Allah) i.e. the disbelievers of Mecca swore by Allah before the coming of the Prophet (pbuh) (their most binding oath) by Allah, (that if a warner) a warning Messenger (came unto them they would be more tractable) they would be swifter in responding and more guided in the religion (than any of the nations) than the Jews and Christians; (yet, when a warner) Muhammad (pbuh) (came unto them) with the Qur'an (it aroused in them naught save repugnance) from it,