וְאֶ֨לֶף אִ֣ישׁ עִמּוֹ֮ מִבִּנְיָמִן֒ וְצִיבָ֗א נַ֚עַר בֵּ֣ית שָׁא֔וּל וַחֲמֵ֨שֶׁת עָשָׂ֥ר בָּנָ֛יו וְעֶשְׂרִ֥ים עֲבָדָ֖יו אִתּ֑וֹ וְצָלְח֥וּ הַיַּרְדֵּ֖ן לִפְנֵ֥י הַמֶּֽלֶךְ׃
베냐민 사람 일천 명이 저와 함께 하고 사울의 사환 시바도 그 아들 열다섯과 종 스무 명으로 더불어 저와 함께 하여 요단 강을 밟고 건너 왕의 앞으로 나아오니라
Siftei Chakhamim
Onkelos translates it וצלח [he split] as in וצלחו [they split]... It seems that Rashi is not proving from Onkelos [that ויבקע means “splitting”]. Rather, he is explaining that [also Onkelos’s translation of] צלח is “splitting,” as in (Shmuel II 19:18): “They split (וצלחו) the Jordan.”
Rashi
ויבקע AND HE CLEAVED [THE WOOD] — Its rendering in the Targum וצלח has the same meaning as the verb in (2 Samuel 19:18) And they rushed into the Jordan”, which signifies cleaving the waters; old French fendre; English to split.