1 Chronicles 11:5-7

New Catholic Bible

⁵ The inhabitants of Jebus said to David, “You will never enter.” Nevertheless, David captured the citadel of Zion, that is, the City of David. ⁶ David had said, “Whoever leads the attack on the Jebusites will be the commander-in-chief.” Joab, the son of Zeruiah, led it so he became the commander.

⁷ David lived in the citadel, and thus it was called the City of David.