First Corinthians 7:39-40 gives blanket permission for remarriage after the death of one's spouse—although it is not mandatory:
Can widows / widowers remarry? What is the biblical view of remarriage after death of a spouse?
A wife is bound to her husband as long as he lives. But if her husband dies, she is free to be married to whom she wishes, only in the Lord. Yet in my judgment she is happier if she remains as she is. And I think that I too have the Spirit of God.
Marriage vows are only binding while both parties live. There is no marriage in heaven (Matthew 22:30), so there is no marriage of the dead.
In the Old Testament, remarriage after the death of a spouse was usually a matter of children. After Sarah died, Abraham married Keturah who gave him six sons. God supported Levirate marriages (wherein a childless widow married her late husband's brother to provide an heir for her husband) so that a man's property would remain with his descendants and a woman would be cared for by her son (Deuteronomy 25:5-6). This ensured the woman had an option to remarry since, as a widow, she could not provide a political advantage for her father's family.
With the advent of the church, women didn't have to remarry after the death of their spouses. The church as Christ's body was impelled to provide for faithful, righteous, elderly widows who had no family support (1 Timothy 5:3-10). In a way, the church was compensating such women for the kingdom work they performed (verse 10). Older widows with family were to be cared for by their family. Younger widows, however, were not to be supported by the church. It was doubted as to whether a young widow could truly dedicate the rest of her life to God and the church, rejecting all possibility of remarrying. (There were exceptions, of course, as in Anna in Luke 2:36-37.) An older widow had a resume of sorts, showing her lifetime of prudent and godly living. Younger women were tempted not only by the thought of marriage, but also by the idleness that comes with financial stability and no direct responsibilities. Since tending a family was one of the very few career choices young women had, it was better they were occupied with that.
In a culture where the desire to be married was assumed and, for women, the idea of support without family was nearly impossible, remarriage after a spouse's death was a great attraction on a purely practical level. That is not always the case in modern times. Women do not need the protection and support of a spouse to serve God, and men never did (see: Jesus, Paul, many of the Old Testament prophets). The Bible clearly says that widows and widowers are free to remarry, but it does not say if they should. Remarriage is as much a matter for spiritual discernment as the initial marriage. It is good to be married, and it is good to be single. Only God knows which is best for each person.
If a person divorces and remarries, is it always going to be adulterous?
What does the Bible teach about marriage?
When is the right time for marriage?
In marriage how do the two become one flesh?
What does the Bible say about engagement?
Truth about Marriage