I was a slave, so I asked the Messenger of Allah ﷺ, "May I give in charity from my masters' wealth?"He replied, "Yes, and the reward will be shared equally between you both."
كنت مملوكا فسألت رسول الله ﷺ أأتصدق من مال موالي بشيء؟ قال: نعم والأجر بينكما نصفان.
Muslim narrated it in the Book of Zakat (1025) via Hafs bin Ghiyath, from Muhammad bin Zayd, from Umayr, who related the hadith. He also narrated it through another route from Umayr with the wording, "My master ordered me to cut up some meat and preserve it. A poor man came to me, so I fed him from it. My master found out about this and beat me. I went to the Messenger of Allah ﷺ and told him what happened, so he summoned my master and asked him, 'Why did you beat him?' He said, 'He gives away my food without my permission.' The Messenger of Allah said, 'The reward is shared between the two of you.'"As for his being called "Abi al-Lahm" (the one who refuses meat), he was given this name because during the Jahiliyyah he had forbidden meat for himself and refused to eat what was slaughtered upon the idols, so he came to be called Abi al-Lahm.