The Messenger of Allah ﷺ said, "When you are three, two should not converse privately without the third."
حدثنا هشيم عن يحيى بن سعيد عن محمد بن يحيى بن حبان
قال رسول الله ﷺ إذا كنتم ثلاثة فلا يتناج اثنان دون واحد
Its isnad is sahih, but it is disconnected, because in 4871 it was narrated by Muhammad bin Yahya from a man from his father.Yahya bin Saeed is Ansari.Muhammad bin Yahya bin Habban bin Munqidh Ansari was a reliable tabii. Ibn Main, Abu Hatim, Nasai, and others confirmed his reliability, and the confirmation of his reliability by Ibn Ishaq will come at 11836. Bukhari gave his biography in al-Kabir 1/1/265-266.The hadith was narrated by Abu Dawud 4:414 through the route of Abu Salih from Ibn Umar, and it will come from the narration of Abu Salih at 4685. Munziri said, Bukhari and Muslim also related it from the hadith of Nafi from Ibn Umar in a similar wording.It will also come in similar wording from the hadith of Abdullah bin Dinar from Ibn Umar at 4564, and from the hadith of Nafi from Ibn Umar at 4664.Its meaning has already appeared several times from the hadith of Ibn Masud, the last of which was at 4436.