Meaning of the verse “And were it not that all mankind would have become of one community…” [az-Zukhruf 43:33]
Question

What is the interpretation of the meaning of the verses 33, 34, 35 of Soorat az-Zukhruf? What do we learn from them? Is the message in these verses an answer to those who say: Why does the disbeliever live a life of luxury whilst the Muslim lives a life of hardship, poverty and misery? Is there any connection between these verses and the story of Qaroon? Was there a reason for the revelation of these verses?
Praise be to Allah.Allah, may He be exalted, says (interpretation of the meaning): 
“And were it not that all mankind would have become of one community (all disbelievers, desiring worldly life only), We would have provided for those who disbelieve in the Most Beneficent (Allah), silver roofs for their houses, and elevators (and stair-ways, etc. of silver) whereby they ascend,
And for their houses, doors (of silver), and thrones (of silver) on which they could recline,
And adornments of gold. Yet all this (i.e. the roofs, doors, stairs, elevators, thrones etc. of their houses) would have been nothing but an enjoyment of this world. And the Hereafter with your Lord is only for the Muttaqoon (the pious)” [az-Zukhruf 43:33-35]. 
Ibn Katheer (may Allah have mercy on him) said: 
That is, were it not that many ignorant people would believe that Our bestowal of wealth is indicative of Our love for the recipient, so they would all come under the banner of disbelief for the sake of wealth – this is what was meant by the words of Ibn ‘Abbaas, al-Hasan, Qataadah, as-Suddi and others – “We would have provided for those who disbelieve in the Most Beneficent (Allah), silver roofs for their houses, and elevators (and stair-ways)” that is, staircases and steps of silver – this was stated by Ibn ‘Abbaas, Mujaahid, Qataadah, as-Suddi, Ibn Zayd and others –
“whereby they ascend” that is, climb up. 
“And for their houses, doors” and locks on their doors
“and thrones (of silver) on which they could recline” that is, all of that would be of silver
“And adornments of gold”. 
Then He says: “Yet all this (i.e. the roofs, doors, stairs, elevators, thrones etc. of their houses) would have been nothing but an enjoyment of this world” that is, this is only part of that transient, temporary world that is insignificant before Allah, may He be exalted. In other words, because of the good things they do in this world, He hastens to give them fine food and drink, so that when they come to the Hereafter, they will have no good deeds for which the reward will still be outstanding. 
Then He says: “And the Hereafter with your Lord is only for the Muttaqoon (the pious)” that is, it is only for them and will not be shared with anyone else. 
End quote from Tafseer Ibn Katheer (7/226-227). See also Tafseer as-Sa ‘di (p. 765) 
Secondly: 
The lesson we learn from these verses comes in the context of criticism of the life of this world, for it is not worth the weight of a gnat’s wing. If Allah so willed, He could give the disbeliever everything he desires of this world, because it is so insignificant to Him and he (the disbeliever) is so insignificant to Him, may He be glorified. But by His mercy, He does not grant him all types of worldly gain, lest people be tempted by that and hasten to disbelieve, and they forget the hereafter. 
Ibn Abi Shaybah (7/105) narrated with a saheeh isnaad from Ibn Mas‘ood who said: Verily Allah grants worldly gain to those whom He loves and those whom He does not love, but He does not grant faith to anyone except those whom He loves. If Allah loves a person, He grants him faith.                          
Therefore what the Muslim must do, if he is living a life of hardship in this world and he sees the disbeliever living a life of ease, is not to be sad; rather he should think positively of Allah and understand that Allah, may He be glorified and exalted, is not withholding worldly gain from him because he is insignificant to Him, and He does not give it to the disbeliever as an honour to him; rather it is the other way round. 
Al-Bukhaari (4913) and Muslim (1479) narrated that ‘Umar (may Allah be pleased with him) entered upon the Messenger of Allah (blessings and peace of Allah be upon him), and he had been sleeping on a reed mat that had left marks on his side, and beneath his head was a pillow of leather stuffed with palm fibres. ‘Umar said: I saw the marks left by the reed mat on his side, and I wept. He said: What is making you weep? I said: O Messenger of Allah, verily Chosroes and Caesar are living the lives they live, but you are the Messenger of Allah! He said: “Does it not please you that this world is for them and the Hereafter is for you?” 
Thirdly: 
We do not know of any specific reason for the revelation of these verses; rather they come under the same category as other verses that condemn this world and those who care only about it, and urge people to seek the hereafter and its reward and status, and what Allah has prepared in it for its people of eternal bliss, as Allah, may He be exalted, says (interpretation of the meaning):
“The life of this world is only the enjoyment of deception (a deceiving thing)” [Aal ‘Imraan 3:185]
“And the life of this world is nothing but play and amusement. But far better is the house in the Hereafter for those who are Al-Muttaqoon (the pious). Will you not then understand?” [al-An‘aam 6:32]. 
With regard to the story of Qaroon, it is a practical, real-life example, and definitive proof, that highlights the message of these verses and others which condemn this world and show how the people whose main focus is this world were distracted by it from the hereafter, and they were content with it and thus were distracted from obeying and worshipping Allah, and how they were punished in this world. 
If people gain all luxuries and all good things in this world, they become insolent and transgress, and they forget to give thanks for the blessings. 
Fear of its temptation should make one lose interest in it and focus on the hereafter, and it should prompt one to use whatever blessings one has been given in obedience to Allah, for that is part of perfect gratitude. 
Allah, may He be exalted, says (interpretation of the meaning):
“That home of the Hereafter (i.e. Paradise), We shall assign to those who rebel not against the truth with pride and oppression in the land nor do mischief by committing crimes. And the good end is for the Muttaqoon (pious)” [al-Qasas 28:83]. 
For more information, please see the answer to question no. 84091  . 
And Allah knows best..