Why did David take Goliath's head to Jerusalem?

[tonychanyt]

1 Samuel 17:

54a David took the Philistine’s head and brought it to Jerusalem.

Gill:

why he carried it to Jerusalem is not easy to say, this not being a royal city, nor was it wholly in the hands of the Israelites; part of it indeed was in the possession of Judah and Benjamin, but the stronghold of Zion was possessed by the Jebusites; and it is generally thought that it was to the terror of them that the head of Goliath was carried there.

Goliath was a mighty Philistine warrior, but David cut off his head. He took the trophy and displayed it in Jerusalem as a warning to the Jebusites that their heads might be next. David might have set his sights on Jerusalem as his future capital city. This act foreshadowed David's future role as king and his eventual conquest of Jerusalem.