ک ب بk-b-b
(ن) كَبَّ يَكُبُّ كَبًّاkabba yakubbu kabban (original form: كَبَبَ يَكْبُبُkababa yakbubu): to throw down headlong, to cast on the face. ﴿فَكُبَّتْ وُجُوْهُهُمْ فِي النَّارِ﴾ (An-Naml 27:90)
Form IV (ifʿāl) أَكَبَّ يُكِبُّ إِكْبَابًاakabba yukibbu ikbāban: to fall on one's face oneself; مُكِبّmukibb (active participle, ism fāʿil). A morphological point worth noting: contrary to the general rule, here the bare triliteral (thulāthī mujarrad) is transitive and the verb form (bāb) ifʿāl is intransitive — the grammarians have counted it among the few words where the hamzah is not for transitivity. Only once in the Quran: ﴿أَفَمَنْ يَّمْشِيْ مُكِبًّا عَلٰى وَجْهِهِۦ﴾ (Al-Mulk 67:22).