Musnad Ahmad 30:1659

Al-Khuza'i narrated to us, he said: Sulayman ibn Bilal narrated to us, from Kathir ibn Zayd, from al-Walid ibn Rabah, from Abu Hurayrah, from the Prophet, peace and blessings of Allah be upon him, who said: "The lowest among them may grant protection on behalf of my Ummah."