Tafsir of Al-Insan 76:10

"Indeed, We fear from our Lord a Day" — meaning the punishment of a Day. This is based on the estimation of an added noun (genitive), or the fear of it is a metonymy for fearing what is in it.

"Abus (frowning)" — the faces will frown, in the sense of a figurative attribution, as in "his day is fasting." It is narrated from Ibn Abbas that the disbeliever will frown on that Day until sweat flows from between his eyes like tar. Or, it is compared to a frowning lion, based on a hidden, imaginative metaphor; however, it is not hidden that frowning is not necessarily an attribute of the lion, though it is famously described as such. Thus, regarding the imaginative metaphor, it is said to be a hyperbolic simile.

"Qamtari (distressing/severe)" — intensely frowning. It is also said to mean severe and difficult, where its evil is intertwined, part of it with another. It is also said to mean long, which is a narration from Ibn Abbas. The form "Qamatir" also exists, and they cited the lines of Asad ibn Naghisa:

I have endured wars every day, A lion of evil, qamtari. O sons of our uncle, do you remember our trial Upon you when the day was qamatir?

And the saying of another. Al-Zajjaj preferred the first, saying: "Al-Qamtari is one who frowns until the space between his eyes gathers." It is said, "aqmatarat the she-camel" if she raises her tail, constricts her parts, and gathers her sides, as if she does that when she reaches old age. It is also said she does so to drop her fetus. Its derivation, according to him, is based on what is said regarding "qatar" via great derivation, with the 'm' being extra. This is not binding upon Al-Zajjaj, for it is permissible that it is derived in that manner from "qamt," meaning when one ties and gathers its extremities. In Al-Bahr, it is said: "aqmatara," so it is "muqmatir," "qamtari," and "qamatir" if it becomes difficult and severe. There is disagreement regarding this weight (pattern), and most grammarians do not affirm "afma'ala" among the weights of verbs.

This sentence can be interpreted as the cause for their benevolence and their aforementioned actions; as if it were said: "We do for you what we do because we fear a Day whose description is such and such; therefore, we hope by that that our Lord, Exalted and Majestic is He, will protect us from its evil." It may also be the cause for the desire for recompense and gratitude; meaning, "We do not seek from you recompense, because of our fear of the punishment of Allah Almighty if we seek recompense out of happenstance." To these two interpretations, the author of Al-Kashshaf alluded, and in Al-Kashf, he said the second is more fitting so that the statement "for the sake of Allah" remains pure, unadulterated by a share of the self—neither in bringing benefit nor repelling harm. If it is made the cause for the feeding, it is explained in the sense: "We have specifically devoted the benevolence to His Face, Exalted is He, because we fear the Day of His recompense, and whoever fears it must be sincere." This would also be a valid interpretation.