وإذا مس اﻻإنسان ضر دعا ربه منيبا إليه
And when some hurt touches man, he cries to his Lord, turning to Him in repentance.
means, at times of need, he prays to Allah and seeks His help alone, not associating anything with Him.
This is like the Ayah:
وإذا مسكم الضر فى البحر ضل من تدعون إﻻ إياه فلما نجكم إلى البر أعرضتم وكان اﻻنسن كفورا
And when harm touches you upon the sea, those that you call upon vanish from you except Him. But when He brings you safe to land, you turn away. And man is ever ungrateful. (17:67)
Allah says:
ثم إذا خوله نعمة منه نسي ما كان يدعو إليه من قبل
But when He bestows a favor upon him from Himself, he forgets that for which he cried for before,
means, at the time of ease, he forgets that supplication and prayer.
This is like the Ayah:
وإذا مس اﻻنسن الضر دعانا لجنبه أو قاعدا أو قايما فلما كشفنا عنه ضره مر كٲن لم يدعنا إلى ضر مسه
And when harm touches man, he invokes Us, lying on his side, or sitting or standing. But when We have removed his harm from him, he passes on as if he had never invoked Us for a harm that touched him! (10:12)
وجعل لله أندادا ليضل عن سبيله
and he sets up rivals to Allah, in order to mislead others from His path.
means, at times of ease, he associates others in worship with Allah and sets up rivals to Him.
قل تمتع بكفرك قليﻼ إنك من أصحاب النار
Say: "Take pleasure in your disbelief for a while, surely, you are (one) of the dwellers of the Fire!''
means, say to those whose way this is, `enjoy your disbelief for a while!'
This is a stern threat and solemn warning, as in the Ayat:
قل تمتعوا فٳن مصيركم إلى النار
Say: "Enjoy! But certainly, your destination is the Fire!'' (14:30)
نمتعهم قليﻼ ثم نضطرهم إلى عذاب غليظ
We let them enjoy for a little while, then in the end We shall oblige them to (enter) a great torment. (31:24)