Musnad Ahmad 789:38

Yahya ibn Adam narrated to us, Qutbah narrated to us, from al-A’mash, from a man from the people of Basra, from Abu Barzah al-Aslami, who said: The Messenger of Allah (ﷺ) called out until he made the young women in their homes hear, and he said: "O assembly of those who have believed with their tongues, while faith has not entered their hearts: do not backbite the Muslims, and do not pursue their private faults. For whoever pursues the private fault of his brother, Allah will pursue his private fault until He disgraces him in his own house."