It is reported commonly] RV 'It is actually reported.' His father's wife] The father may have been dead or separated from his wife: the stepson had then married her. The Corinthian Church was evidently unconscious that there was anything sinful in such a union. Had the man and woman been living in sin without marriage the Church could scarcely have made even a show of defending their conduct. The persons referred to in 2 Corinthians 7:12 have no connexion with this incident: see notes there.
Related Commentaries of 1 Corinthians 5:1
1 Corinthians 5:1
1 It is reported commonly that there is fornication among you, and such fornication as is not so much as named among the Gentiles, that one should have his father's wife.