It is narrated from Sayyiduna Malik bin Nadlah al-Jushami (may Allah be pleased with him) that he came to the Prophet (peace and blessings be upon him) in a poor garment, and the Prophet (peace and blessings be upon him) said to him: "Do you have wealth?" He said: Yes, Allah has given me every kind of wealth. He (peace and blessings be upon him) said: "What kind of wealth?" He said: Allah has given me horses and slaves. The Prophet (peace and blessings be upon him) said to him: "When Allah gives you wealth, let the trace of His blessing and generosity be seen upon you."
Then he said: "Are your camels born with complete ears?" He said: Are they born in any other way? He (peace and blessings be upon him) said: "Then you take your blade and cut the tips of the ears and say: This is a bahirah; and you slit some of them and say: These are surum." He said: I do that. He (peace and blessings be upon him) said: "Do not do it, for everything that Allah has given you is lawful for you."
Then he said to the Prophet (peace and blessings be upon him), and he had not yet accepted Islam at that time: O Muhammad! What do you think: if I stayed with a man and he did not host me and did not recognise my right, and then fortune pressed him and brought him to me, should I show him hospitality or repay him? He (peace and blessings be upon him) said: "Rather, show him hospitality."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 16659