19 The construction is a verbal hendiadys: לֹא תֹאסִפוּן לָתֵת (lo’ to’sifun latet, “you must not add to give”). The imperfect tense acts adverbially, and the infinitive becomes the main verb of the clause: “you must no longer give.”
20 The expression “for making bricks” is made of the infinitive construct followed by its cognate accusative: לִלְבֹּן הַלְּבֵנִים (lilbon hallévenim).
21 Heb “as yesterday and three days ago” or “as yesterday and before that.” This is idiomatic for “as previously” or “as in the past.”
22 The jussive יֵלְכוּ (yelékhu) and its following sequential verb would have the force of decree and not permission or advice. He is telling them to go and find straw or stubble for the bricks.

In other versions

“You shall no longer give the people straw to make bricks, as in the past; let them go and gather straw for themselves.

“You are no longer to supply the people with straw for making bricks; let them go and gather their own straw.

“Don’t continue to supply the people with straw for making bricks, as before. They must go and gather straw for themselves.

“Do not supply any more straw for making bricks. Make the people get it themselves!

“You must no longer give straw to the people to make the bricks like before. Let them go and gather straw for themselves.

Ye shall no more give the people straw to make brick, as heretofore: let them go and gather straw for themselves.

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