Allah says: {Are they better, or the people of Tubba' and those before them} of the disbelievers? Meaning: they are not better than them; He is frightening them with the punishment.
قَالَ الله: ﴿أَهُمْ خَيْرٌ أَمْ قَوْمُ تُبَّعٍ وَالَّذِينَ مِنْ قَبْلِهِمْ﴾ من الْكفَّار أَي: أَنهم لَيْسُوا بِخَير مِنْهُم؛ يخوفهم بِالْعَذَابِ.