Tafsir Ibn Kathir -> Surah Ta-Ha -> Allah commanded Musa to go to Fir`awn to convey the Message Allah said,

﴿اذْهَبْ إِلَى فِرْعَوْنَ إِنَّهُ طَغَى ﴾

(Go to Fir`awn! Verily, he has transgressed.) This means, "Go to Fir`awn, the king of Egypt, whom you left Egypt fleeing from, and invite him to the worship of Allah alone, Who has no partners. Command him to treat the Children of Israel well and to not torment them. For verily, he has transgressed, oppressed, preferred the worldly life and forgotten the Most High Lord.''