(15) باب تَحْرِيمِ مُنَاجَاةِ الاِثْنَيْنِ دُونَ الثَّالِثِ بِغَيْرِ رِضَاهُ
Ibn Umar reported Allah's Messenger (ﷺ) as saying:
When there are three (persons), two should not converse secretly between themselves to the exclusion of the (third) one. (ID)
Reference (ID): Sahih Muslim 2183 a (ID)
In-book reference (ID): Book 39, Hadith 48 (ID)
USC-MSA web (English) reference(deprecated numbering scheme): Book 26, Hadith 5419 (ID)