The Messenger of Allah (sal Allahu alaihi wa sallam) said: "The talebearer will not enter Paradise." [Sahih Muslim]
A man came to Hasan al-Basri and said: "Such-and-such man talked about you in an unfavourable manner."
"At his home."
"What were you doing in his home?"
"I went there for a feast."
"What did you eat there?"
"Such-and-such delicious food. I ate from all eight different dishes."
"Fearless wretch! You have managed to digest eight different dishes, but you could not digest only these words. Get out of my sight!"
The unity of Muslims is destroyed by tale-bearing. If one has committed the sin of hearing someone being backbitten about they should not compound their sin by informing the victim (or others) of what they heard. Hearts are soured when a person's words against one are brought to their attention. Backbiting and tale-bearing are more deadly than venom for the harmony of hearts required for the Muslims to be able to love and take care of one another.