It is narrated from Sayyiduna Malik bin Nadlah al-Jushami (may Allah be pleased with him) that he said: I came to the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) saw me in a poor state and said to me: "Do you have wealth?" I said: Yes, every kind of wealth, which Allah has given me: camels, cattle, horses and slaves. He (peace and blessings be upon him) said: "When Allah gives you good, let His blessing and His generosity be seen upon you."
I said: O Muhammad, and I had not yet accepted Islam at that time, what do you think: if I stayed with a man and he did not show me hospitality and did not consider that I had any right, and then fortune struck him with hardship and brought him to stay with me, should I repay him for what he did, or show him hospitality? He (peace and blessings be upon him) said: "No, rather show him hospitality."
Then he said to me: "Are your camels born with full ears?" I said: Are camels born in any other way? He (peace and blessings be upon him) said: "Then you take a blade and cut their ears and say: This is a bahirah; and you take your blade and slit their ears and say: These are surum?" I said: We do that. He (peace and blessings be upon him) said: "Then do not do it. Everything that Allah has given you is lawful. The blade of Allah is sharper than your blade, and the arm of Allah is stronger than your arm." The narrator said: And in this respect the tribe of Qays were the foremost of all the Arabs. This wording is from the narration of Ibn Raja'.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 16658