When is forgetting a mitzvah?
And Rav Huna says: A large sheaf of grain that contains two se’a has both the status of a sheaf and the status of a heap with regard to the halakhot of forgotten sheaves that must be left for the poor. It has the status of a sheaf, as the principle is that two sheaves that were inadvertently left in the field are considered forgotten sheaves that must be left for the poor, whereas three sheaves need not be left for the poor, but rather the owner of the field may go back and take them for himself. In this regard a two-se’a sheaf is considered one sheaf, so if one forgot two sheaves andalso this sheave that contains two se’a, the three together are three sheaves and are not considered forgotten sheaves that must be left for the poor. And it has the status of a heap, as we learned in a mishna (Pe’a 6:6): In the case of a sheaf that contains two se’a, if one forgets it in a field, it is not considered a forgotten sheaf that must be left for the poor, as its size and importance grant it the status of a heap, rather than a sheaf.
One of the many ways that we take care of the poor is by leaving the corners of our fields for them, tithing a 10th of our produce for them, and when we harvested anything that we forget, we donate to the poor as well.
So, when is forgetting a mitzvah? When it benefits the poor, the foreigner, the widow and those who are vulnerable in society.


