Tafsir of Ad-Dukhan 44:21

But if you believe me not, then keep away from me and leave me alone. means, `then let us leave one another alone and live in peace until Allah judges between us.' After Musa, may Allah be pleased with him, had stayed among them for a long time, and the proof of Allah had been established against them, and that only increased them in disbelief and stubbornness, he prayed to his Lord against them, a prayer which was answered. Allah says:

وقال موسى ربنا إنك ءاتيت فرعون ومﻼه زينة وأمواﻻ فى الحيوة الدنيا ربنا ليضلوا عن سبيلك ربنا اطمس على أمولهم واشدد على قلوبهم فﻼ يومنوا حتى يروا العذاب اﻻليم

قال قد أجيبت دعوتكما فاستقيما

And Musa said: "Our Lord! You have indeed bestowed on Fir`awn and his chiefs splendor and wealth in the life of this world, our Lord! That they may lead men astray from Your path. Our Lord! Destroy their wealth, and harden their hearts, so that they will not believe until they see the painful torment.'' Allah said: "Verily, the invocation of you both is accepted. So you both keep to the straight way.''... (10:88-89) And Allah says here:

فدعا ربه أن هوﻻء قوم مجرمون