In megillas Rus (2:15-16) we read
וַיְצַו בֹּעַז אֶת-נְעָרָיו לֵאמֹר, גַּם בֵּין הָעֳמָרִים תְּלַקֵּט--וְלֹא תַכְלִימוּהָ.
וְגַם שֹׁל-תָּשֹׁלּוּ לָהּ, מִן-הַצְּבָתִים; וַעֲזַבְתֶּם וְלִקְּטָה, וְלֹא תִגְעֲרוּ-בָהּ.
However the mishna in peah 5:6 (5:5 in some editions) dictates that a field owner not show favoritism to the poor who come to collect. How then was Boaz allowed to do this?