Musnad Ahmad 1034:166

Waki’ narrated to us, from Sufyan, from Abu Ishaq, from Silah ibn Zufar, from Hudhayfah, who said: Al-‘Aqib and Al-Sayyid came to the Prophet, peace and blessings of Allah be upon him, and said: "Send with us a trustworthy man." The Prophet, peace and blessings of Allah be upon him, said: "I will send with you a man who is trustworthy, trustworthy, trustworthy." He said: The companions of the Messenger of Allah, peace and blessings of Allah be upon him, knelt down on their knees for it [hoping to be chosen]. He said: So he sent Abu Ubaydah ibn al-Jarrah.