וַיַּעֲל֥וּ בְּבַֽעַל־פְּרָצִים֮ וַיַּכֵּ֣ם שָׁ֣ם דָּוִיד֒ וַיֹּ֣אמֶר דָּוִ֔יד פָּרַ֨ץ הָֽאֱלֹהִ֧ים אֶת־אוֹיְבַ֛י בְּיָדִ֖י כְּפֶ֣רֶץ מָ֑יִם עַל־כֵּ֗ן קָֽרְא֛וּ שֵֽׁם־הַמָּק֥וֹם הַה֖וּא בַּ֥עַל פְּרָצִֽים׃
So they came up to Baal-perazim, and David smote them there; and David said: ‘God hath broken mine enemies by my hand, like the breach of waters.’ Therefore they called the name of that place Baal-perazim.
Rashi on I Chronicles
And they went up to Baal-Perazim which was later called Baal-Perazim because of the incident that occurred there. God has broken my enemies in my hand meaning that they fled and were broken off from one another.
Rashi on I Chronicles
like a breach of waters like waves of water that break from their place and fall somewhere else.