Is it a mistake for someone to say that if God were to punish the righteous and admit them into Hell, He would be unjust? What is the correct doctrine on this issue, and do the words of Ibn Taymiyyah, Ibn al-Qayyim, and Ibn Uthaymeen support this statement?

The torture of the obedient and the blameless is considered an injustice that God is far removed from. Ahl al-Sunnah (definition) believe that injustice is placing something in other than its rightful place. God is capable of injustice, but He has declared Himself far removed from it and has forbidden it upon Himself. Some scholars believe that injustice is intrinsically impossible for God because He acts within His own dominion, or that injustice is possible but God does not commit it due to His perfect essence. If God were to punish the inhabitants of the heavens and the earth, it would be their right and their deserving of punishment, not an injustice, because their deeds are not sufficient for their salvation, and their need for His forgiveness and mercy is like their need for His protection and provision. As for causing pain to animals, Ibn al-Jawzi believes that human intellect may be perplexed by its wisdom, but divine obligation necessitates submission and refraining from objection, and that animals were created to serve humans, and the pain of slaughter is minor or imperceptible in some cases.