2 Samuel 5:4

David was thirty years old when he began to reign, and he reigned forty years.

1 Chronicles 26:31

Of the Hebronites was Jerijah, the chief among the Hebronites, according to the generations of his fathers. In the fortieth year of the reign of David they were sought for, and there were found among them mighty men of valour at Jazer of Gilead.

1 Chronicles 29:27

And the time that he reigned over Israel was forty years; he reigned seven years in Hebron, and he reigned thirty-three years in Jerusalem.

Luke 3:23

And Jesus himself began to be about thirty years of age, being (as was supposed) the son of Joseph, who was the son of Heli,

1 Kings 2:11

The days that David reigned over Israel were forty years; he reigned seven years in Hebron, and he reigned thirty-three years in Jerusalem.

1 Chronicles 3:4

These six were born unto him in Hebron, and there he reigned seven years and six months, and in Jerusalem he reigned thirty-three years.

Treasury of Scripture Knowledge

Summary

David was thirty years old when he began to reign, and he reigned forty years.

Thirty

Bible References

Thirty

Luke 3:23
And Jesus himself began to be about thirty years of age, being (as was supposed) the son of Joseph, who was the son of Heli,

Forty

1 Chronicles 26:31
Of the Hebronites was Jerijah, the chief among the Hebronites, according to the generations of his fathers. In the fortieth year of the reign of David they were sought for, and there were found among them mighty men of valour at Jazer of Gilead.
1 Chronicles 29:27
And the time that he reigned over Israel was forty years; he reigned seven years in Hebron, and he reigned thirty-three years in Jerusalem.