Abu Dawud Book 8, Hadith Number 2761.

Narated By Dhu Mikhbar : Hassan ibn Atiyyah said: Makhul and Ibn Zakariyya went to Khalid ibn Ma’dan, and I also went along with them. He reported a tradition on the authority of Jubayr ibn Nufayr. He said: Go with us to Dhu Mikhbar, a man from the Companions of the Prophet (PBUH). We came to him and Jubayr asked him about peace. He said: I heard the Apostle of Allah (PBUH) say: You will make a secure peace with the Byzantines, then you and they will fight an enemy behind you.