Musnad Ahmad 5:453

Waki’ narrated to us, Sufyan narrated to us, from Sa’d ibn Ibrahim, from ‘Abdullah ibn Shaddad, from ‘Ali, who said: I never heard the Messenger of Allah, peace and blessings of Allah be upon him, ransom anyone with his parents except for Sa’d ibn Malik. For I heard him say to him on the day of Uhud: "Shoot, Sa’d! May my father and mother be ransomed for you."