There is nothing to suggest that the years in question are figurative as opposed to literal, especially given the specific details of 2 Samuel 5:5. Even so, there are certain ideas which the numbers do serve to communicate. Thirty years of age was the age of Joseph when he became a ruler in Egypt (Genesis 41:46) and also that of Jesus when he began his ministry (Luke 3:23). David’s overall reign of forty years matches that of his predecessor, Saul (Acts 13:21), as well as that of his son and successor, Solomon (1 Kings 11:42).1 Quite possibly, thirty years represents the age when a man reached his maturity (see Numbers 4:47) and forty years represents the period of a complete generation (see Psalm 95:10).
4 David était âgé de trente ans lorsqu'il devint roi, et il régna quarante ans.