Musnad Ahmad 30:2039

Sulayman ibn Dawud narrated to us, he said: Isma'il informed us, he said: Al-'Ala' informed me, from his father, from Abu Hurayrah, that the Messenger of Allah (may Allah bless him and grant him peace) said: "No one bears the hardship of Al-Madinah and its severity, except that I will be an intercessor for him on the Day of Resurrection, or a witness."