Two persons should not talk privately ignoring the third, for that will grieve him.  

قَالَ رَسُولُ اللَّهِ ﷺ لاَ يَنْتَجِي اثْنَانِ دُونَ الثَّالِثِ فَإِنَّ ذَلِكَ يُحْزِنُهُ  

Malik related to me from Nafi from Abdullah ibn Umar that the Messenger of Allah ﷺ said, "Two must not converse secretly to the exclusion of another person."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا كَانَ ثَلاَثَةٌ فَلاَ يَتَنَاجَى اثْنَانِ دُونَ وَاحِدٍ  

[Machine] The translation of the given sentence is:

"The Messenger of Allahﷺ used to forbid when there were three individuals that two should hold a private conversation excluding the third."  

كَانَ رَسُولُ اللهِ ﷺ يَنْهَى إِذَا كَانَ ثَلَاثَةُ نَفَرٍ أَنْ يَتَنَاجَى اثْنَانِ دُونَ الثَّالِثِ  

"The Messenger of Allah ﷺ forbade two to converse (privately) to the exclusion of a third." (Using translation from Ibn Mājah 3776)   

قَالَ رَسُولُ اللَّهِ ﷺ «لَا يَتَنَاجَى اثْنَانِ دُونَ الثَالِثٍ»  

[Machine] The Messenger of Allah ﷺ said, "Two should not hold a secret conversation excluding the third."  

قَالَ رَسُولُ اللهِ ﷺ «لَا يَتَنَاجَى اثْنَانِ دُونَ الثَّالِثِ»  

"لَا يَنْتَجِي اثْنَانِ دُونَ الثَّالِث؛ فَإِنَّ ذَلِكَ يُحْزِنُهُ".