Musnad Abu Ya'la al-Mawsili 160:238

Surayj ibn Yunus narrated to us, Ibrahim ibn Khuthaym ibn 'Arak ibn Malik narrated to us, from his father, from his grandfather, from Abu Hurayrah, from the Prophet (peace and blessings of Allah be upon him), who said: "Be gentle regarding Allah, be gentle. For were it not for bowing old men, humble youths, suckling infants, and grazing cattle, the punishment would have been poured down upon you in torrents."