וַיַּרְא֙ חֹתֵ֣ן מֹשֶׁ֔ה אֵ֛ת כָּל־אֲשֶׁר־ה֥וּא עֹשֶׂ֖ה לָעָ֑ם וַיֹּ֗אמֶר מָֽה־הַדָּבָ֤ר הַזֶּה֙ אֲשֶׁ֨ר אַתָּ֤ה עֹשֶׂה֙ לָעָ֔ם מַדּ֗וּעַ אַתָּ֤ה יוֹשֵׁב֙ לְבַדֶּ֔ךָ וְכָל־הָעָ֛ם נִצָּ֥ב עָלֶ֖יךָ מִן־בֹּ֥קֶר עַד־עָֽרֶב׃
Vendo, pois, o sogro de Moisés tudo o que ele fazia ao povo, perguntou: Que é isto que tu fazes ao povo? por que te assentas só, permanecendo todo o povo junto de ti desde a manhã até a tarde?
Sforno on Exodus
מדוע אתה יושב לבדך?, why are only you dealing with public affairs?
Rashbam on Exodus
מדוע אתה יושב לבדך?, and as a result of your being the sole judge the entire people have to stand in line before you from morning to evening.
Mekhilta d'Rabbi Yishmael
(Exodus 18:14) "And Moses' father-in-law saw": What did he see? He saw him sitting like a king sitting on his throne and all paying attendance upon him, whereupon he said to him: "What is this that you are doing to the people? Why are you sitting alone?"