The finality and importance of following the Messenger

وَيَوْمَ يَعَضُّ ٱلظَّالِمُ عَلَىٰ يَدَيْهِ يَقُولُ يَـٰلَيْتَنِى ٱتَّخَذْتُ مَعَ ٱلرَّسُولِ سَبِيلًا

And the Day the wrongdoer will bite on his hands [in regret] he will say, "Oh, I wish I had taken with the Messenger a way.