Inna rabbaka yabsutu arrizqa liman yashao wayaqdiru innahu kana biAAibadihi khabeeran baseera (surah Al Isra: 30)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(17:30) Your Lord provides plentifully to whom He wills and withholds His provisions from anyone He pleases, for He is fully aware of the condition of His servants and observes them closely. *30

Inna Rabbaka yabsuturrizqa limai yashaaa`u wa yaqdir; innahoo kaana bi`ibaadihee Khabeeram Baseera

*30) That is, "Man cannot realize the wisdom of the disparity of wealth among the people" : therefore, man should not try to interfere by artificial means with the natural distribution of wealth. It is wrong to level down natural inequality or to aggravate it by artificial means so as to make it unjust. Both the extremes are wrong. The best economic system is that which is established on the Divine Way of the division of wealth.
As a result of the realization of the wisdom of economic disparity, no such problems arose which might have made that disparity an evil in itself so as to demand the creation of a classless society. On the contrary, in the righteous society established at AI-Madinah on these Divine principles which are akin to human nature, the economic differences were not artificially disturbed. But by means of moral and legal reforms these became the means of many moral, spiritual and cultural blessings and benefits instead of becoming the means of injustice. Thus, the wisdom of the disparity created by the Creator of the Universe was practically demonstrated at Al-Madinah.