"And your companion is not mad," meaning: Muhammad [peace be upon him], and that is because of the saying of the polytheists that he is mad.
﴿وَمَا صَاحبكُم بمجنون﴾ يَعْنِي: مُحَمَّدا [ﷺ] وَذَلِكَ لِقَوْلِ الْمُشْرِكِينَ إِنَّهُ مَجْنُونٌ
