וַיִּזְעֲק֣וּ בְנֵֽי־יִשְׂרָאֵל֮ אֶל־יְהוָה֒ וַיָּקֶם֩ יְהוָ֨ה לָהֶ֜ם מוֹשִׁ֗יעַ אֶת־אֵה֤וּד בֶּן־גֵּרָא֙ בֶּן־הַיְמִינִ֔י אִ֥ישׁ אִטֵּ֖ר יַד־יְמִינ֑וֹ וַיִּשְׁלְח֨וּ בְנֵי־יִשְׂרָאֵ֤ל בְּיָדוֹ֙ מִנְחָ֔ה לְעֶגְל֖וֹן מֶ֥לֶךְ מוֹאָֽב׃
But when the children of Israel cried unto the LORD, the LORD raised them up a saviour, Ehud the son of Gera, the Benjamite, a man left-handed; and the children of Israel sent a present by him unto Eglon the king of Moab.
Rashi on Judges
Whose right arm was immobile. Yonasan renders "A man whose right arm was shrunken." "Gamid" in the Aramaic always indicates something shrunken by disease, "retrait", "shrunk" in old French. He could not utilize his right arm. In Hebrew, "closed", as in "Let not the well close its mouth over me."4Tehilim, 69:16. His right arm was "closed"—he could not utilize it.
Metzudat Zion on Judges
A matter of contraction as in Psalm 69: 16 "Don't let the mouth of the Pit not close over me." It is to say it is as if his right hand was contracted because he didn't extend it.