Musnad Ahmad 30:1590

Narrated to us Ishaq ibn Sulayman, narrated to us Dawud ibn Qays, from Zayd ibn Aslam, from Abu Salih, from Abu Hurayrah, that the Messenger of Allah, peace and blessings of Allah be upon him, said: "Whoever grants respite to one in financial difficulty, or waives it for him, Allah will shade him in the shade of His Throne on the Day of Resurrection."