ומפני ביטול עניים — שלא יהו עניים יושבין ומשמרין ״עכשיו מניח בעל הבית פאה״. ומפני חשד — שלא יהיו עוברין ושבין אומרים: תבא מארה לאדם שלא הניח פאה בשדהו. ומשום ״בל תכלה״. אטו כולהו לאו משום ״בל תכלה״ נינהו? אמר רבא: מפני הרמאין.
And due to causing the poor to be idle; so that the poor, who have no way of knowing when he is going to cut the grain and where in the field he is going to leave the pe’a, will not be sitting and observing until he designates the pe’a and constantly saying to themselves: Now the owner of the field is placing pe’a. Now that he leaves the pe’a in a defined area at the end of his field, and the poor people know exactly where they can receive their portion, they need not waste their time in anticipation. And due to suspicion; if one leaves the pe’a in the middle of the field, the poor will come and take their portion immediately when he designates the area of pe’a. When the owner then continues to cut and harvest the rest of the grain in the field, the pe’a will not be noticeable. Insisting that he leave pe’a at the end of the field ensures that passersby will not say: A person who did not leave pe’a in his field should be cursed. We learned that the 4th reason is due to the verse: You should not wholly reap. The Talmud wonders: Aren’t all of these reasons due to: You should not wholly reap? All of the reasons explain that one may not reap his entire field and must leave pe’a at the end of his field. Rava said: The meaning of the last reason is that pe’a is separated that way due to cheaters. There is concern that a person would not leave pe’a at all. He would claim that he already separated it in the middle of his field and that the poor already came and took it. In order to bolster the mitzva of pe’a, the rabbis instituted that it must be separated specifically at the end of one’s field. In terms of the discussion in the Talmud, apparently, the desire to avoid arousing suspicion is a factor taken into consideration in determining halakha.