In a company of three, two should not speak privately leaving out the third in their presence

the Prophet ﷺ said, "When there are three persons, then two of them should not speak privately excluding the third."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ: «إِذَا كَانُوا ثَلاَثَةٌ فَلاَ يَتَنَاجَى اثْنَانِ دُونَ الثَّالِثِ۔»  

The Prophet ﷺ said, "When you are three persons sitting together, then no two of you should hold secret counsel excluding the third person until you are with some other people too, for that would grieve him."  

قَالَ النَّبِيُّ ﷺ {إِذَا كُنْتُمْ ثَلاَثَةً فَلاَ يَتَنَاجَى رَجُلاَنِ دُونَ الآخَرِ حَتَّى تَخْتَلِطُوا بِالنَّاسِ أَجْلَ أَنْ يُحْزِنَهُ}