Abu Hurairah (RAA) narrated that The Messenger of Allah (ﷺ) said:
"Otherwise he will be required to work to pay for his freedom, but he must not be overburdened." Agreed upon. (JA)
English reference (JA): Book 15, Hadith 1467 (JA)
Arabic reference (JA): Book 15, Hadith 1423 (JA)