Musnad Ahmad 30:1617

Zakariya ibn 'Adi narrated to us, Ibn al-Mubarak informed us, from 'Isa ibn Yazid, from Jarir ibn Yazid, from Abu Zur'ah, from Abu Hurayrah, from the Prophet, peace and blessings of Allah be upon him, who said: "A prescribed punishment (hadd) that is established on the earth is better for the people than that they should be rained upon for thirty—or forty—mornings."