The Quran

Preface

استَغفِر لَهُم أَو لا تَستَغفِر لَهُم إِن تَستَغفِر لَهُم سَبعينَ مَرَّةً فَلَن يَغفِرَ اللَّهُ لَهُم ۚ ذٰلِكَ بِأَنَّهُم كَفَروا بِاللَّهِ وَرَسولِهِ ۗ وَاللَّهُ لا يَهدِي القَومَ الفاسِقينَ

Yusuf Ali

Whether thou ask for their forgiveness, or not, (their sin is unforgivable): if thou ask seventy times¹ for their forgiveness, God will not forgive them: because they have rejected God and His Messenger. and God guideth not those who are perversely rebellious.

An awful warning for those who actively oppose the Cause of God. The Holy Prophet was by nature full of mercy and forgiveness. He prayed for his enemies. But in such a case even his prayers are nullified by their attitude of rejecting God.