1 Chronicles 11:7 KJV

And David dwelt in the castle; therefore they called it the city of David.

David raised to the throneDavid was brought to possess the throne of Israel after he had reigned seven years in Hebron, over Judah only. God's counsels will be fulfilled at last,...

2 Samuel 5:7 Nevertheless David took the strong hold of Zion: the same is the city of David.
1 Chronicles 11:5 And the inhabitants of Jebus said to David, Thou shalt not come hither. Nevertheless David took the castle of Zion, which is the city of David.
Psalms 2:6 Yet have I set my king upon my holy hill of Zion.

From OpenBible.info, most relevant first.

Castle A tower
Cities Royal
David Makes conquest of Jerusalem
Jerusalem The citadel of Mount Zion, occupied by David, and called the CITY OF DAVID
Zion Captured from the Jebusites by David

DavidBeloved, the eighth and youngest son of Jesse, a citizen of Bethlehem. His father seems to have been a man in humble life. His mother’s...

And David דָּוִיד dāwîd דָּוִד Proper name
dwelt וַיֵּשֶׁב wayyēšeb יָשַׁב Verb · qal sequential imperfect, third person masculine singular · with and
in the castle בַּמְצָד bamṣād מְצַד Noun · feminine singular · with preposition with the
therefore they called עַל ʿal Preposition כֵּן kēn Demonstrative קָרְאוּ qārĕʾww קָרָא Verb · qal perfect, third person common plural
it the city לוֹ lô Preposition · with suffix: third person masculine singular עִיר ʿîr עִיר Noun · feminine singular construct
of David דָּוִיד dāwîd דָּוִד Proper name

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