Anas ibn Malik  ؓ reported: The Messenger of Allah ﷺ said to me:

يَا بُنَيَّ إِنْ قَدَرْتَ أَنْ تُصْبِحَ وَتُمْسِيَ لَيْسَ فِي قَلْبِكَ غِشٌّ لِأَحَدٍ فَافْعَلْ

O my son, if you are able every morning and evening to remove any rancor from your heart towards anyone, then do so.

Then the Prophet ﷺ said:

يَا بُنَيَّ وَذَلِكَ مِنْ سُنَّتِي وَمَنْ أَحْيَا سُنَّتِي فَقَدْ أَحَبَّنِي وَمَنْ أَحَبَّنِي كَانَ مَعِي فِي الْجَنَّة

O my son, that is my tradition (sunnah) and whoever revives my tradition has loved me, and whoever loves me will be with me in Paradise.

Source: Sunan al-Tirmidhi