Tafsir of Al-Qamar 54:8

Surah Al-Qamar (The Moon): Verse 8

{مهطعين إلى الداع}

This means they will be rushing toward the Caller (the one who summons them on the Day of Judgment), submitting to him.

{يقول الكافرون هذا يوم عسر}

It is possible that the operative verb governing the accusative case of yawm (day) in the preceding verse, {يوم يدعو الداع} (The Day the Caller calls), is implied here. That is, on the Day the Caller calls, "the disbelievers will say, 'This is a difficult Day.'"

This statement carries two benefits:

1. A Warning to the Believer: It alerts the believer that this Day will be extremely difficult specifically for the disbeliever, just as Allah says: {فذلك يومئذ عسير * على الكافرين غير يسير} (That will be a difficult Day, not easy for the disbelievers) (Al-Muddaththir: 9-10). Meaning, for them, it is difficulty without ease.
2. Shared Experience (with a Difference): Both the believer and the disbeliever share the initial events—emerging from the graves as if they were scattered locusts and rushing toward the Caller. However, the believer rushes out of fear, not feeling secure from punishment until God grants him assurance through faith, rewarding him. The disbeliever, remaining in his state, will then say, "This is a difficult Day."

{كذبت قبلهم قوم نوح فكذبوا عبدنا وقالوا مجنون وازدجر}

(The people of Noah denied before them, and they denied Our Servant, and said, "A madman," and were deterred/rebuked.)