Musnad Abu Ya'la al-Mawsili 108:120

Abu Bakr narrated to us, Mu'awiyah ibn Hisham narrated to us, Sufyan narrated to us, from Dawud, from 'Amir, from Jabir ibn 'Abdullah, who said: When the Prophet, may Allah bless him and grant him peace, met the leaders (nuqaba') of the Ansar, he said to them: "Will you shelter me and protect me?" They said: "What is for us?" He said: "For you is Paradise."