Zazan reported,

I was with Ibn Umar when he called for a slave of his and set him free. Then he said, "I have no reward in this. It is not worth this much," or "it does not weigh this much. I heard the Messenger of Allah ﷺ say, 'Whoever strikes a slave of his with a punishment he did not deserve, or wrongs him, or slaps him,'" — Abdul-Rahman was uncertain — "'then his expiation is to set him free.'"

Ahmad 5267

Sahih

حدثنا عبد الرحمن عن سفيان عن فراس أخبرني أبو صالح

عن زاذان قال

كنت عند ابن عمر فدعا غلاما له فأعتقه ثم قال ما لي فيه من أجر ما يسوى هذا أو يزن هذا سمعت رسول الله ﷺ يقول من ضرب عبدا له حدا لم يأته أو ظلمه أو لطمه شك عبد الرحمن فإن كفارته أن يعتقه

أحمد 5267صحيح
Contents
Reference
Commentary
Ayat
Collection
Musnad Ahmad
Book
Abdullah bin Umar
Numbering
Darussalam 5267
Ahmad 5267