Sa'id bin 'Abdur Rahman سعيد بن عبد الرحمن بن أبي · General Behavior (Kitab Al-Adab)

The Prophet (ﷺ) said: There is no sin more fitted to have punishment meted out by Allah to its perpetrator in advance in this world along with what He stores up for him in the next world than oppression and severing ties of relationship.