When you reap your harvest in your field, and forget a sheaf in the field, you shall not go back to get it; it shall be for the stranger, the fatherless, and the widow, that the LORD your God may bless you in all the work of your hands. Deuteronomy 24:19
Wait, I thought there was no mercy in the law, but wait again, is this a tax? The law here says 'forget', not, 'you must leave one'. It is amazing to see God's mercy at work on both sides. For there is no demand to leave any amount, and if none were forgotten then that is okay too. However, if greed steps in and the farmer were to make extra effort to return to fetch that forgotten sheaf then violation of the law abounds. It is what happens in the heart that condemns one before the law.
There are several more verses to read concerning the harvest and all were about faith in God. That is, faith in not trying to retrieve for yourself every last bit of the harvest, from not beating the olive trees a second time to not gleaning the grapes until every last one is found. Those who had nothing or no way to make a living could go out into the fields and gather for themselves under the law. And by showing mercy, the farmer gained a blessing from the Lord.
Having the Lord's blessing on the work of our hands is so important in this life that, should we lose it to greed or selfishness, we would sorely miss it.Rejoice in a generous day in Christ the Lord!