Musnad Ahmad 1007:99

Harun ibn Ma'ruf narrated to us, Abdullah ibn Wahb narrated to us, Abu Sakhr informed me, that Yahya ibn al-Nadr al-Ansari narrated to him, that he heard Abu Qatadah say: I heard the Messenger of Allah, may Allah bless him and grant him peace, say upon the pulpit to the Ansar: "Verily, the people are my undergarment (dithar), and the Ansar are my inner garment (shi'ar). If the people were to travel through a valley and the Ansar were to travel through a mountain pass, I would follow the mountain pass of the Ansar. And were it not for the Hijrah, I would have been a man from the Ansar. So whoever is placed in authority over the Ansar, let him do good to those among them who do good, and let him overlook those among them who do evil. And whoever frightens them has frightened this one who is between these two," and he pointed to himself, may Allah bless him and grant him peace.