וַיֹּ֣אמֶר אֵלֶ֔יהָ עֲמֹ֖ד פֶּ֣תַח הָאֹ֑הֶל וְהָיָה֩ אִם־אִ֨ישׁ יָב֜וֹא וּשְׁאֵלֵ֗ךְ וְאָמַ֛ר הֲיֵֽשׁ־פֹּ֥ה אִ֖ישׁ וְאָמַ֥רְתְּ אָֽיִן׃
西西拉又對她說：«請你站在帳棚門口；若有人來問你說：『這裡有人嗎？』你就說：『沒有。』»
Rashi
Stand at the entrance to the tent. Be zealous about it. Some interpret עֲמֹד [lit. "stand"] as לַעֲמוֹד, "to stand".11This interpretation adds the ל, which does not actually appear in the text, so that the reading is “He told her to stand at the entrance.” According to the literal textual interpretation, the reading is, “He told her, stand at the entrance.” This is problematic, as the masculine עֲמוֹד, rather than עִמֽדִי, is inappropriate in addressing a woman. The additional ל solves this difficulty by transforming the command, עֲמוֹד, “stand”, into the infinitive לַעֲמוֹד, “to stand.”
Radak
Stand: It is an infinitive: And he said to her to stand at the entrance of the tent.