(50) باب لاَ يَتَنَاجَى اثْنَانِ دُونَ الثَّالِثِ
It was narrated from Abdullah that the Messenger of Allah(ﷺ) said:
"When you are three, two should not converse (privately) to the exclusion of their companion, because that makes him sad."
Reference: Sunan Ibn Majah 3775
In-book reference: Book 33, Hadith 120
English translation: Vol. 5, Book 33, Hadith 3775