עַ֣ד ׀ חֹ֣דֶשׁ יָמִ֗ים עַ֤ד אֲשֶׁר־יֵצֵא֙ מֵֽאַפְּכֶ֔ם וְהָיָ֥ה לָכֶ֖ם לְזָרָ֑א יַ֗עַן כִּֽי־מְאַסְתֶּ֤ם אֶת־יְהוָה֙ אֲשֶׁ֣ר בְּקִרְבְּכֶ֔ם וַתִּבְכּ֤וּ לְפָנָיו֙ לֵאמֹ֔ר לָ֥מָּה זֶּ֖ה יָצָ֥אנוּ מִמִּצְרָֽיִם׃
but a whole month, until it come out at your nostrils, and it be loathsome unto you; because that ye have rejected the LORD who is among you, and have troubled Him with weeping, saying: Why, now, came we forth out of Egypt?’
Rashi on Numbers
עד חדש ימים BUT EVEN A WHOLE MONTH [SHALL YE EAT] — This was said in reference to the comparatively virtuous, who languish on their beds and only afterwards their soul departs from them; in reference to the wicked, however, it states, (v. 33) “and while the flesh was yet between their teeth [the wrath of the Lord glowed against the people]”. Thus is it taught in the Sifrei Bamidbar 94. But in the Mechilta d'Rabbi Yishmael 16:13:1 (on Exodus 16:13) just the opposite is taught: the wicked ate the flesh and were in agony thirty days, while as for the comparatively virtuous, “the flesh was yet between their teeth, etc.” (they suffered no prolonged agony, but died immediately).
Sforno on Numbers
והיה לכם לזרא, they will eat so much of it that that it will cause an excess which in turn will produce sickness. This is what Assaph in Psalms 78,31 spoke about.
Rashbam on Numbers
עד אשר יצא מאפכם, as per Onkelos, i.e. until you will vomit it.