וְעַתָּ֗ה יֵֽשֶׁב־נָ֤א עַבְדְּךָ֙ תַּ֣חַת הַנַּ֔עַר עֶ֖בֶד לַֽאדֹנִ֑י וְהַנַּ֖עַר יַ֥עַל עִם־אֶחָֽיו׃
Now therefore, let thy servant, I pray thee, abide instead of the lad a bondman to my lord; and let the lad go up with his brethren.
Rashi on Genesis
'ישב נא עבדך וגו LET THY SERVANT ABIDE etc. — For all purposes I am superior to him in strength — whether for battle or for service as a slave.
Sforno on Genesis
ועתה ישב נא עבדך תחת הנער, therefore I beg you to let me be the slave in lieu of the lad so that I will not have to remain a sinner against my father for the rest of my life.
Or HaChaim on Genesis
ישב נא עבדך, "may your servant stay, etc." Although Yehudah had undertaken to bring back Benjamin personally, (43,9) he now relied on the dictum that a messenger appointed by a person can discharge that person's obligation as well as the person who has appointed the messenger (Berachot 34).