Sahih Muslim 215

It is reported on the authority of Ibn 'Umar that the Messenger of Allah (may peace and blessings be upon him) said: Any person who called his brother: O unbeliever (has in fact done an act by which this unbelief) would return to one of them...

It is reported on the authority of Abu Dharr that he heard the Messenger of Allah (may peace and blessings be upon him) saying: No person who claimed knowingly anyone else as his father besides (his own) committed nothing but infidelity, and he..

It is narrated on the authority of Abu Huraira that the Messenger of Allah (may peace and blessings be upon him) observed: Do not detest your fathers; he who detested his father committed infidelity. ..

It is reported on the authority of Sa'd b. Abi Waqqas: Both of my ears heard the Messenger of Allah saying this: He who claimed the fatherhood of anyone else besides his real father knowingly (committed a great sin) ;Paradise is forbidden to him...

Sa'd and Abu Bakra each one of them said: My ears heard and my hearing preserved it that Muhammad (peace and blessings be upon him) observed: He who claimed for another one his fatherhood besides his own father knowingly that he was not his..

It is narrated on the authority of 'Abdullah b. Mas'ud that the Messenger of Allah (may peace and blessings be upon him) observed: Abusing a Muslim is an outrage and fighting against him is unbelief. Zubaid said: I asked Abu Wa'il: Did you hear it..