עִנּ֣וּ בַכֶּ֣בֶל רגליו [רַגְל֑וֹ] בַּ֝רְזֶ֗ל בָּ֣אָה נַפְשֽׁוֹ׃
מע האָט געפּײַניקט אין קײטן זײַן פֿוס, אין אײַזן איז אַרײַנגעטאָן געװאָרן זײַן לײַב;
Rashi
his soul was placed in irons Said Rav Huna the son of Idi: She [Potiphar’s wife] made him a “shirtua” under his beard, so that if he bent his face over, the “shirtua” would wound him. שרתוע means a forked, suspended spear.