Arabic Text
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِذَا كَانَ ثَلاَثَةٌ فَلاَ يَتَنَاجَى اثْنَانِ دُونَ وَاحِدٍ " .
English Translation
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.
This hadith is from Sahih Muslim, one of the most rigorously authenticated collections in Islamic scholarship. No editorial opinion is added.