It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever attributes himself to anyone other than his father (starts calling someone else his father), or any slave who calls someone other than his master his master, upon him is the curse of Allah, the angels, and all people. On the Day of Resurrection, Allah, the Lord of Glory, will not accept any obligatory or voluntary act from him."