Musnad Abu Ya'la al-Mawsili 243:23

Uthman ibn Abi Shaybah narrated to us, Jarir narrated to us, from Ata’ ibn al-Sa’ib, from Abu Bakr, from his father, Abu Musa, who said: The Messenger of Allah (ﷺ) said: "If a stone were thrown into Hell, it would fall for seventy autumns before it reached its bottom."