Musnad Ahmad 30:1396

'Affan narrated to us, Wuhayb narrated to us, Hisham narrated to us, from Salih ibn Abi Salih al-Samman, from his father, from Abu Hurayrah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "No one bears the hardship of Medina and its difficulty, except that I will be an intercessor for him, or a witness, on the Day of Resurrection."