וַיִּשְׁלַ֤ח אֵהוּד֙ אֶת־יַ֣ד שְׂמֹאל֔וֹ וַיִּקַּח֙ אֶת־הַחֶ֔רֶב מֵעַ֖ל יֶ֣רֶךְ יְמִינ֑וֹ וַיִּתְקָעֶ֖הָ בְּבִטְנֽוֹ׃
Metzudat David on Judges
And Ehud Sent: (his sword) when he was still struggling to stand
Metzudat Zion on Judges
And it got stuck: Thrust and insertion. As in Samuel 2:18:14 "and it was thrusted in the heart of Abshalom."