"Then they will be thrown into it [Hell]," meaning: they will be cast into it; that is, the polytheists. "They and the deviants," meaning: the devils.
Muhammad said: "Fukubkibu" (they will be thrown) has its origin in "kubbibu" (they were cast), from your saying: "kababtu al-ina'a" (I overturned the vessel). The middle 'ba' was replaced by a 'kaf' due to the burden of having three 'ba's appearing consecutively.
﴿فكبكبوا فِيهَا﴾ أَيْ: قُذِفُوا فِيهَا؛ يَعْنِي: الْمُشْرِكِينَ ﴿هم والغاوون﴾ يَعْنِي: الشَّيَاطِينَ.
قَالَ مُحَمَّدٌ: ﴿فَكُبْكِبُوا﴾ أَصْلُهُ: كُبِّبُوا؛ مِنْ قَوْلِكَ: كَبَبْتُ الْإِنَاءَ، فَأُبْدِلَ مِنَ الْبَاءِ الْوُسْطَى كَافًا؛ اسْتِثْقَالًا لِاجْتِمَاعِ ثَلَاثِ بَاءَاتٍ.
