וַיֹּ֤אמֶר יְהוָה֙ אֶל־מֹשֶׁ֔ה עַד־אָ֥נָה יְנַאֲצֻ֖נִי הָעָ֣ם הַזֶּ֑ה וְעַד־אָ֙נָה֙ לֹא־יַאֲמִ֣ינוּ בִ֔י בְּכֹל֙ הָֽאֹת֔וֹת אֲשֶׁ֥ר עָשִׂ֖יתִי בְּקִרְבּֽוֹ׃
Der Herr sprach zu Mose: Wie lange noch soll mich dieses Volk verwerfen, und wie lange noch wollen sie nicht an mich glauben bei allen Zeichen, die ich getan in seiner Mitte?
Rashi on Numbers
עד אנה means HOW LONG (while אנה is used of place — “where”, עד אנה denotes time - "until when").
Sforno on Numbers
?עד אנה ינאצוני, “What is the limit of their spurning Me? How long am I supposed to tolerate the disdain with which they treat Me?
Or HaChaim on Numbers
ויאמר ה׳….עד אנה ינאצוני העם הזה, G'd said to Moses: "how long will this nation continue to spurn Me?" G'd's question was intended to forestall Moses praying on behalf of the people; it is similar to G'd having said הניחה לי, "let Me be," when G'd had told Moses about the golden calf (Exodus 32,10). The absence of the word לאמור in our verse is a hint that Moses should not speak.