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

The faith of a servant is not upright until his heart is upright, and his heart is not upright until his tongue is upright. A man will not enter Paradise if his neighbor is not secure from his evil.

لَا يَسْتَقِيمُ إِيمَانُ عَبْدٍ حَتَّى يَسْتَقِيمَ قَلْبُهُ وَلَا يَسْتَقِيمُ قَلْبُهُ حَتَّى يَسْتَقِيمَ لِسَانُهُ وَلَا يَدْخُلُ رَجُلٌ الْجَنَّةَ لَا يَأْمَنُ جَارُهُ بَوَائِقَهُ

Source: Musnad Aḥmad 12636, Grade: Hasan