Why do English bibles change “Yearn for Purity” (נַשְּׁקוּ בַר) in Psalm 2:12 to “Kiss the Son” or “Kiss his Son”?

We read in Tehillim 2:12 [MT], "Yearn for Purity, lest He be angry and your-way will perish when suddenly His-wrath will kindle. Happy [are] all who take refuge in-Him" (נַשְּׁקוּ בַ֡ר פֶּן יֶאֱנַ֚ף וְתֹ֬אבְדוּ דֶ֗רֶךְ כִּֽי יִבְ…