And the infinitive before a verb that comes with a negation:

It sometimes teaches that the verb was proper to be, but was not; בוש לא יבושו (they are not at all ashamed)⁸⁸ בכה לא תבכה (you shall weep no more)⁸⁹.

footnotes: ⁸⁸ Jeremiah 6:15. ⁸⁹ Isaiah 30:19.

And it sometimes teaches that the verb means precisely; ואכול לא תאכלוהו (but you shall in no wise eat of it)⁹⁰ - but benefit is permitted.

Jeremiah 6:15 uses the language בוש לא יבושו when it says,הבישו כי תועבה עשו גם בוש לא יבושו גם הכלים לא ידעו לכן יפלו בנפלים בעת פקדתים יכשלו אמר יהוה (They shall be put to shame because they have committed abomination; yea, they are not at all ashamed, neither know they how to blush; therefore they shall fall among them that fall, at the time that I punish them they shall stumble, says the LORD), meaning that they should be ashamed, but they are not.

Isaiah 30:19 uses the language בכה לא תבכה when it says,כי עם בציון ישב בירושלם בכו לא תבכה חנון יחנך לקול זעקך כשמעתו ענך (For, O people that dwell in Zion at Jerusalem, you shall weep no more; He will surely be gracious to you at the voice of your cry, when He shall hear, He will answer you), meaning that they should weep, but they will not weep.

footnotes: ⁹⁰ Leviticus 7:24.