﴿ وَقَالُوا۟ يَٰٓأَيُّهَا ٱلَّذِى نُزِّلَ عَلَيْهِ ٱلذِّكْرُ إِنَّكَ لَمَجْنُونٌۭ ﴾

“And yet, they [who deny the truth] say: "O thou unto whom this reminder has [allegedly] been bestowed from on high: verily, thou art mad!”

(And they) this refers to 'Abdullah Ibn Umayyah al-Makhzumi and his host who (say) to Muhammad (pbuh): (O thou unto whom the Reminder is revealed) O you who claim that Gabriel brought you the Qur'an, (lo! thou art indeed a madman!) who is inventing lies.