Before the Mishnah, the Gemara stated the opinion that it is better that the chaver do a light sin of tithing from one place to another rather than causing an am haaretz to do a bigger sin. Question from Shabbas where we said that one should not remove dough from the wall of an oven even before it bakes in order to save his fellow Yid from the terrible sin of chillul Shabbos!
Zev Sack, Boston, USA
Zev, Baruch She-Kivanta! Your question is asked by Tosfos. Tosfos answers that here the chaver has a part in the sin of the am haaretz, because he told him to pluck the produce which leads the am haaretz to think that the chaver has already separated Terumos uMaasros.
Kesivah vaChasimah Tovah
Dovid Bloom