Why Allah threatens punishment while He is in no need of people
30-11-2017 | IslamWeb
Question:
Assalaamu alaykum. Why has Allaah threatened to punish us if we do not obey His orders? He is not in need of anyone, so why does He punish us if we do not obey Him? I hope that you will give me a direct reply instead of referring me to a link. May Allaah reward you.
Answer:
All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad 
is His slave and Messenger.
First of all, you should know that Allah Almighty has absolute wisdom in His Words and Actions, because their source is absolute Knowledge and ultimate Wisdom, as He is the All-Knowing, the All-Wise; Allah says (what means): {And the word of your Lord has been fulfilled in truth and in justice. None can alter His words, and He is the Hearing, the Knowing.} [Quran 6:115]
Ibn Taymiyyah 
said about the above verse, “It means that the Quran is truthful in its reports and just in its provisions.”
Secondly, the wisdom of Allah in His Creation may be grasped or not grasped, because the minds of people fall short of comprehending it. So they should just surrender to Him, regardless of whether the wisdom is known; Allah says (what means): {It is not for a believing man or a believing woman, when Allah and His Messenger have decided a matter, that they should [thereafter] have any choice about their affair. And whoever disobeys Allah and His Messenger has certainly strayed into clear error.} [Quran 33:36]
Thirdly, there is no doubt that Allah Almighty did not create His Creation for His need for them; rather, it is the creation who need His Help, while He does not need any of them. Allah does not need their acts of worship, as no act of obedience of a person will benefit Him, and no sin of a person will harm Him. The benefit of their act of obedience is for them, and the harm of their sin is upon them. Allah says (what means): {…and Allah is the Free of need, while you are the needy. And if you turn away, He will replace you with another people; then they will not be the likes of you.} [Quran 47:38]
Allah also says (what means): {Whoever does righteousness - it is for his [own] soul; and whoever does evil [does so] against it. And your Lord is not ever unjust to [His] servants.} [Quran 41:46]
Besides, Allah said in a Qudsi (sacred) hadeeth:
“…O My servants, you will not attain harming Me so as to harm Me, and you will not attain benefiting Me so as to benefit Me. O My servants, even if the first amongst you and the last amongst you and even the whole of mankind and jinn become as pious as the heart of the most pious amongst you, this would not add anything to My Dominion (Power). O My servants, even if the first amongst you and the last amongst you and the whole of mankind and jinn become as wicked as the heart of the wickedest man amongst you, this would not decrease anything from My Dominion (Power)… O My servants, these are only your deeds which I record for you and then shall reward you for them; if anyone of you finds good, he should praise Allah; and if anyone of you finds other than that, he should not blame anyone but himself.” [Muslim]
Fourthly; one of the greatest aspects of the wisdom behind creation is trial so that the righteous person would be distinguished from the evil one, and the truthful one would be distinguished from the liar. Allah says (what means): {[He] Who created death and life to test you [as to] which of you is best in deed - and He is the Exalted in Might, the Forgiving.} [Quran 67:2]
Since there are righteous people and evil people, then Allah’s wisdom necessitates that the righteous be rewarded and the evil be punished. This is even the norm among the people; it is not strange or objectionable to those who have a sound mind that the criminal is punished because of his crime. The fact that Allah does not need their worship and their acts of obedience does not necessitate that He does not punish them when they deserve punishment. The punishment is because of their disobedience and not because He needs their acts of obedience – far Exalted is Allah above needing their obedience.
Allah knows best.