The word "akabba" is a derivative of "kabba". It is said: I threw it down and it fell, which is one of the oddities and exceptions. Similar to this is: The wind cleared the clouds, so they cleared. And it is not like that, nor is there anything from the form of "af'al" that is derivative, and only the bearers of Sibawayh's book master such matters. Rather, "akabba" is from the same category as "anfadha" and "alamma". Its meaning is: he entered into the act of falling down, and became one who has fallen. Likewise, "aqsha'a" refers to the clouds: he entered into clearing. The derivatives of "kab" and "qash" are: "inkabba" and "inqasha'a". If you ask: What is the meaning of "walking on his face"? And how does it contrast with "walking upright on a straight path"? I say: Its meaning is: he walks in a manner that is uneven in a familiar place, not fully experiencing the ups and downs, so he stumbles every moment and falls on his face, being in a state opposite to that of one who walks upright, that is: standing safe from stumbling and falling. Or he is on a level path with little deviation, unlike the one who is unevenly swaying back and forth on a straight path. It is also possible that it refers to a blind person who cannot find the way, so he continues to fall on his face, and he is not like the upright man with sound sight walking on the guided path. This is a parable for the believer and the disbeliever. And from Qatadah: The disbeliever has fallen into the disobedience of Allah, so Allah will gather him on the Day of Resurrection on his face. And from Al-Kalbi: It refers to Abu Jahl ibn Hisham. And the upright one refers to the Messenger of Allah, blessings and peace be upon him, and it was said: Hamzah ibn Abd al-Muttalib.