David was 30 years old when he became king. And he was king over Israel for 40 years. He ruled over Judah in Hebron for seven years and 6 months. And in Jerusalem he ruled over all Israel and Judah for 33 years. 2 Samuel 5:4-5
大衛登基的時候年三十歲，在位四十年； 在希伯崙作猶大王七年零六個月，在耶路撒冷作以色列和猶大王三十三年。 撒母耳記下 5:4-5