He said, "I came to Ibn Umar after he had freed a slave. He picked up a stick or something from the ground and said, 'There is no more reward in it than the value of this, except that I heard the Messenger of Allah ﷺ say, "Whoever slaps his slave or beats him, his expiation is to free him."'"
قال أتيت ابن عمر وقد أعتق مملوكا، قال: فأخذ من الأرض عودا أو شيئا، فقال: ما فيه من الأجر ما يسوى هذا، إلا أني سمعت رسول الله ﷺ يقول: من لطم مملوكه، أو ضربه، فكفارته أن يعتقه.