3,119. Leket, Peret and Shich'cha

Hilchos Matnos Aniyim 1:4

The preceding rules also apply to leket (gleanings). When harvesting or binding sheaves, one may not gather the stalks that fell. Rather, he must leave them for the needy, as per Leviticus 23:22, "Do not gather the gleanings of your harvest.” If one violated the law by gathering them, he must give them to the needy. This is so even if he already ground them into flour and baked them into bread since the verse says “Leave it for the needy and the convert.” If the grain is destroyed or burned after he gathered it but before he could give it to the needy, he is liable to the penalty of lashes.

Hilchos Matnos Aniyim 1:5

The same is true of loose grapes that fall while being harvested and to undergrown clusters of grapes as per Leviticus 19:10, "Do not harvest undergrown clusters from your vineyard and do not gather loose grapes that fall in your vineyard. You shall leave them for the needy and the convert." Likewise, if one who is binding sheaves forgets a bundle, he may not go back to retrieve it as per Deuteronomy 24:19, "If you forget a sheaf in the field, you may not turn back to take it.” If he violated the law by retrieving it, he must give it to the needy even if he already ground it and baked it because the verse says "They shall be for the convert, the orphan and the widow." This is a Torah obligation. We have therefore seen that these are all prohibitions whose violation can be corrected by obligations. If one violates one of these prohibitions and does not perform the requisite obligation, he is subject to the penalty of lashes.