It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: A Muslim is the brother of another Muslim; he does not oppress him nor does he disgrace him. By the One in whose hand is the soul of Muhammad (peace and blessings be upon him), when separation occurs between two people who love each other, it is the result of the sin of one of them. The Prophet (peace and blessings be upon him) also said: A Muslim has six rights over his brother: when he sneezes, he should say to him "Yarhamukallah" (may Allah have mercy on you); when he falls ill, he should visit him; whether he is present or absent, he should wish well for him in every situation; when he meets him, he should greet him with salam; when he invites him, he should accept his invitation; and when he dies, he should follow his funeral prayer. The Prophet (peace and blessings be upon him) also forbade that a Muslim should abandon his brother for more than three days.