Hadiths about purification of the heart.

Zayd ibn Arqam reported: The Messenger of Allah, peace and blessings be upon him, said:

اللَّهُمَّ آتِ نَفْسِي تَقْوَاهَا وَزَكِّهَا أَنْتَ خَيْرُ مَنْ زَكَّاهَا

O Allah, grant my soul a sense of righteousness and purify it, for you are the best purifier.

Source: Ṣaḥīḥ Muslim 2722, Grade: Sahih

Abu Huraira reported: A man came to the Messenger of Allah, peace and blessings be upon him, and he complained about the hardness of his heart. The Prophet said:

إِنْ أَرَدْتَ تَلْيِينَ قَلْبِكَ فَأَطْعِمْ الْمِسْكِينَ وَامْسَحْ رَأْسَ الْيَتِيمِ

If you want to soften your heart, feed the poor and pat the head of the orphan.

Source: Musnad Aḥmad 7522, Grade: Hasan

Anas ibn Malik reported: The Messenger of Allah, peace and blessings be upon him, said to me:

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

Young man, if you are able every morning and evening to remove any rancor from your heart towards anyone, do so.

Then, the Prophet said to me:

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

 

Young man, that is my Sunnah. Whoever revives my Sunnah has loved me, and whoever loves me will be with me in Paradise.

Source: Sunan al-Tirmidhī 2678, Grade: Hasan

Anas ibn Malik reported: The Prophet, peace and blessings be upon him, said:

لا يَبْلُغُ عَبْدٌ حَقِيقَةَ الإِيمَانِ حَتَّى يُحِبَّ لِلنَّاسِ مَا يُحِبُّ لِنَفْسِهِ مِنَ الْخَيْرِ

The servant does not attain the reality of faith until he loves for people what he loves for himself of goodness.

Source: Ṣaḥīḥ Ibn Ḥibbān 238, Grade: Sahih