Malik related to me from Abdullah ibn Dinar saying, "Abdullah ibnUmar and I were at the house of Khalid ibn Uqba who was away at themarket. A man came who wanted to speak to Abdullah ibn Umar and I wasthe only other person present Abdullah ibn Umar called another man sothat we were four and said to me and the man whom he had called, 'Go alittle way off together, because I heard the Messenger of Allah, mayAllah bless him and grant him peace, say, "Two do not conversesecretly to the exclusion of another.' "'
USC-MSA web (English) reference: Book 56, Hadith 13
Arabic reference: Book 56, Hadith 1826