Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates that the Prophet (peace and blessings be upon him) asked about a man: "Who knows him?" A man among them said: I do. He (peace and blessings be upon him) asked: "What is his name?" He said: I do not know. He (peace and blessings be upon him) asked: "What is his father's name?" He said: I do not know. He (peace and blessings be upon him) asked: "Where is his home?" He said: I do not know. He (peace and blessings be upon him) said: "This is not called knowing (someone), until you know his name, his father's name and his tribe, so that if he falls ill you visit him, and if he dies you attend his funeral."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13180