From Sahih Muslim (Hadith 2598):
This hadith has been narrated on the authority of Zuhri with the same chain of transmitters that a person broke fast in Ramadan whereupon the Messenger of Allah (ﷺ) commanded him to free a slave (as an atonement), and the rest of the hadith is the same as narrated by Ibn Uyaina
Reference: Muslim 2598