וַיָּ֥שָׁב אֶל־אֶחָ֖יו וַיֹּאמַ֑ר הַיֶּ֣לֶד אֵינֶ֔נּוּ וַאֲנִ֖י אָ֥נָה אֲנִי־בָֽא׃
And he returned unto his brethren, and said: ‘The child is not; and as for me, whither shall I go?’
Rashi on Genesis
אנה אני בא WHITHER SHALL I GO? — Whither can I flee from my father’s grief?
Radak on Genesis
וישב, he did not know that the brothers had sold him but thought that he had been stolen from the pit.