Kapłańska 23:22 Halacha: Mishneh Torah, Gifts to the Poor

One who reaps his field should not reap the whole field entirely but rather he should leave a little bit of standing grain for the poor at the edge of the field, as it is written, (Lev. 23:22) You shall not reap all the way to the edges of the field. It is the same whether one is reaping [with a tool] or plucking [by hand], and that which is left is what Scripture refers to as péah [the "edge"].

Just as one must leave [some standing crops] in the field, so too when one gathers the fruit of trees, one should leave a little for the poor. If he does transgress [the negative mitzvah against harvesting one's field completely] and reaps all the field or gathers all the trees' fruit, he should take a little from what he reaped or gathered and give it to the poor, for giving it is a positive mitzvah [divine commandment], as it is said, (Lev. 23:22) You shall leave them for the poor and the stranger. Even if the standing grain is ground, kneaded, and baked into bread, the one who gives from it is considered to have given péah to the poor.¹That is, the first part of the verse, (Lev. 23:22) You shall not reap all the way to the edges of the field, corresponds to the prohibition against reaping all of the field, and the second part of the verse, you shall leave them for the poor and the stranger, corresponds with the injunction to give the food to the poor, no matter what form it is in or how far it has been processed. "Leaving them for the poor and the stranger," therefore, actually indicates actively giving.

And so it is with leket [overlooked gleanings] as one reaps and binds, one may not gather the fallen stalks at the time of reaping, but rather one should leave them for the poor, as it is said, (Lev. 23:22) Or gather the gleanings of your harvest. If one transgresses [the negative mitzvah against reaping one's field completely] and reaped them and even kneaded and baked them, one should give them to the poor, as it is said, (Lev. 23:22) You shall leave them for the poor and the stranger. If it is destroyed or burned after one has gleaned but before one has given to the poor, one deserves punishment.