Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
(We appointed) We have created (immortality) in this worldly life (for no mortal) among the prophets (before thee. What! if thou diest) O Muhammad, (can they be immortal) in this worldly life? This verse was revealed when they said: we will wait until Muhammad dies and then we will find rest.
We have not assigned everlastingness to any mortal before thee. If thou diest, will they be everlasting? Every soul shall taste death.
When a speck of truthfulness appears in someone's heart, the reality of passion for death will show its head from his spirit, for the promise of encounter is there. What sort of spirit would forget the promise of encounter? What sort of heart would seek from someplace else the repose that comes only from contemplating the Real? “The person of faith has no ease without encountering his Lord.”
O dervish, no good fortune is more precious than death. Those who have the religion place the crown of magnificence and generosity on their heads at the gate of death. Those who reap the fruit of the Shariah will find the sigil of good fortune at the door of death. Death is the sanctuary of “There is no god but God.” Death is the doorstep of the kingdom of the resurrection and the passageway to the visitors of the Real. Death is the center of the exaltation of the recognizers, the place anticipated by the spirits of the proximate. Death is the vanguard of solicitude and the prelude to endless kind favor. In the two worlds no one has the ease that the tawḤīd-voicer has in the grave with the One. He took along with him into the dust the banner of the submission and the kettledrum of faith in the resurrection. At the resurrection he will come out of the dust with the banner of the submission and the kettledrum of faith, just as kings enter into their own city.
Dāwūd ṬāÌī was one of the great jurists in outward knowledge. His truthfulness was such that on the night he left this world a call came from the middle of heaven: “O folk of the earth! Surely Dāwūd ṬāÌī has stepped forth to his Lord, and He approves of him.”
One of his disciples said that he saw Dāwūd in the throes of death in a ruined house, intense heat, fallen flat on the earth with his head on a piece of brick, reciting the Qur'an. He said to him, “O Dāwūd, what if you were to go out into the open air?” What would happen if you were kind to yourself for an hour and go out into the open air, so this heat would have less effect on you?
Dāwūd said, “My friend, I want to do that, but I am ashamed before my Lord-that I should move my feet in that in which my soul is at ease.
This soul of mine has never had the upper hand over me, and in this state it is even more appropriate that it not have it.” It was in this state, lying in the dust, that he emptied his frame.
Junayd said, “Whoever lives through his Lord will be transferred from the life of his nature to the life of the root, and that is life in reality. God says, 'We shall surely give him to live a goodly life' [16:97].”
When the disbelievers said that Muhammad (s) would die, the following was revealed: And We did not assign to any human being before you immortality, permanence [of life] in this world. What, if you [are fated to] die, will they be immortal?, in it? No! (The last sentence constitutes the [syntactical] locus of the interrogative of denial).
(Whatsoever is on it (the earth) will perish. And the Face of your Lord full of majesty and honor will remain forever.) 55:26-27.
(then if you die) means, O Muhammad,
(would they live forever) means, they hope that they will live forever after you, but that will not happen; everything will pass away. So Allah says:
كُلُّ نَفْسٍ ذَآئِقَةُ الْمَوْتِ
(Everyone is going to taste death,)
وَنَبْلُوكُم بِالشَّرِّ وَالْخَيْرِ فِتْنَةً
(and We shall test you with evil and with good by way of trial. ) Meaning, "We shall test you, sometimes with difficulties and sometimes with ease, to see who will give thanks and who will be ungrateful, who will have patience and who will despair.'' `Ali bin Abi Talhah reported from Ibn `Abbas:
(and We shall test you) means, We will test you,
بِالشَّرِّ وَالْخَيْرِ فِتْنَةً
(with evil and with good by way of trial.) means, with difficulties and with times of prosperity, with health and sickness, with richness and poverty, with lawful and unlawful, obedience and sin, with guidance and misguidance.
(And to Us you will be returned.) means, and We will requite you according to your deeds.
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
From here the same theme of the conflict between the Holy Prophet and the disbelievers, that was interrupted by vv. 19-33, has been resumed.
This is a brief answer to all those warnings and curses with which the Holy Prophet was being threatened and the conspiracies which the Quraish were hatching against him day and night. On the one hand, the women of the Quraish cursed him because according to them he had ruined their home life by enticing away their kith and kits; while on the other, the chiefs of the Quraish threatened hits with horrible consequences for the propagation of Islam. After the emigration to Habash especially, which almost affected every home of Makkah, these curses and threats increased all the more. This verse is meant to comfort and console the Holy Prophet as well so that he should continue his mission without any fear of their threats.
That is, Allah is always putting human beings to test and trial both through adversity and affluence. This is to judge whether prosperity makes them proud, cruel and slaves of their lusts or they become grateful to Allah. On the other hand, He inflicts adversity upon them in order to see whether they remain within the prescribed and lawful limits or become low-spirited and down-hearted. A sensible person therefore should not be deluded by prosperity and adversity, but should keep their trial element in view and try to pass through it gracefully.