אֵ֣ין ׀ שַׂ֣ר בֵּית־הַסֹּ֗הַר רֹאֶ֤ה אֶֽת־כָּל־מְא֙וּמָה֙ בְּיָד֔וֹ בַּאֲשֶׁ֥ר יְהוָ֖ה אִתּ֑וֹ וַֽאֲשֶׁר־ה֥וּא עֹשֶׂ֖ה יְהוָ֥ה מַצְלִֽיחַ׃ (ס)
전옥은 그의 손에 맡긴 것을 무엇이든지 돌아보지 아니하였으니 이는 여호와께서 요셉과 함께 하심이라 여호와께서 그의 범사에 형통케 하셨더라
Rashi on Genesis
באשר ה' אתו — means BECAUSE THE LORD WAS WITH HIM (i.e. באשר means because).
Siftei Chakhamim
Because God was with him. [Rashi knows this] because the ב of באשר ה' אתו cannot follow its usual meaning, [“when Hashem was with him”]. For it says afterwards, “Whatever he did, Hashem made him succeed” — not sometimes yes and sometimes no.