If a person starts telling you something that you know very well, you should pretend as if you dont know it. Do not rush to reveal your knowledge of it or interfere in his speech. Instead, you should show your attention and concentration.
The honourable Tábi’í, Imam ‘Atá Ibn Abi Rabáh [Rahimahullah] said, “A young man would tell me something, I would listen to him as if I never heard it before, although I may have heard of it even before he was born!”
Khalid Ibn Safwán At-Tamimi [Rahimahullah], who was a companion of two khalifahs, Sayyiduná ‘Umar Ibn ‘Abdul ‘Aziz and Khalifah Hisham Ibn ‘Abdul Malik [Rahimahumullah] said, “If a person tells you something which you have heard before, or news that you already know of, do not interrupt him so as to exhibit your knowledge to those present. This is a sign of being rude and ill-mannered.”
The honourable Imam ‘Abdullah Ibn Wahab Al-Quraishi Al-Misri, who is a companion of Imams Malik, Laith Ibn Sa’d and Thawri [Rahimahumullah] said, “Sometimes, a person would tell me a story that I have heard before his parents had wed, yet I listen as if I never heard it before.”
Sayyiduná Ibrahim Ibn Junaid [Rahimahullah] said, “A wise man once said to his son, “Learn to listen properly just as you learn to speak properly.” “Listening properly means, maintaining eye contact, allowing the speaker to finish the speech, and restraining yourself from interrupting his speech, even if you are aware of what he is saying.”
Khatib Baghdadi [Rahimahullah] said in a poem:
A talk never interrupt
Though you know it in and out