1 Corinthians 7:10 (ESV)

10 To the married I give this charge (not I, but the Lord): the wife should not separate from her husband

Paul now turns to the second group of people: church members who are married. Specifically, he has in view those marriages where both parties are believers (in 1 Corinthians 7:12–16, he will give instructions about marriage between a believer and an unbeliever).

When it comes to this group of people, there is no need for instructions from Paul himself. Jesus (the Lord) has already spoken clearly about this topic, and Paul simply repeats his teaching (see Mark 10:11–12; Luke 16:18). This is why Paul writes that it is not he but the Lord who has given this command.

The words separate (1 Corinthians 7:10) and divorce (1 Corinthians 7:11) are used interchangeably, both pointing to a legal act of divorce. Compare 1 Corinthians 7:13, where Paul speaks of a wife who divorces her husband.