1 Corinthians 7:39–40
39 A wife is bound by law as long as her husband lives; but if her husband dies, she is at liberty to be married to whom she wishes, only in the Lord.
40 But she is happier if she remains as she is, according to my judgment—and I think I also have the Spirit of God.
A wife is bound by the law as long as her husband lives. Marriage only stays in place as long both the husband and wife live. If one dies, the spouse is at liberty to be married to whom she wishes. After the death of a spouse, the living man or woman can marry again if they want to, whomever they desire. Only in the Lord, she needs to find another believer to marry.
But, she is happier if she remains as she is. Paul says, it’s my judgment, but I think she will be happier, and I also have the Spirit of God. He is clarifying how he received his own judgment, meaning, it is still God-breathed/inspired by God. Even though God did not speak in a voice this revelation to him, it is inspired because it is written for us and preserved in Scripture. Paul’s judgment was guided by the Holy Spirit.