"ve'Lo Sis'u alav Chet". Which sin is the Torah referring to?
Rashi: It refers to not taking T'rumos and Ma'asros from one's crops.
Rashbam: It refers to desecrating Terumah and T'rumas Ma'aser by eating them be'Tum'ah.
Targum Yonasan: It refers to eating Terumah and T'rumas Ma'aser be'Tum'ah.
Yevamos, 89b: It refers to separating from bad on to good 1 - and it teaches us that what he did is effective; otherwise why would it be considered a sin?
T'rumos, 1:5: It refers to people who eat from Ma'aser which the owner has given the Levi whilst still in its stalks - before the Levi has separated T'rumas Ma'aser. 2
What are the implications of "ve'Lo Sis'u alav Chet ... " and "Lo Sechalelu ve'Lo Samusu"?
Rashi: It implies that someone who fails to separate the Matnos Kehunah will bear a sin, and 'someone who desecrates (by eating them be?Tum?ah - Rashbam) the Kodshim will die!' 1
Because from a 'No', we can extrapolate a 'Yes'. and vice-versa (See Sifsei Chachamim).
What are the connotations of "Lo Sechal?lu??
Rashbam: Refer to 18:32:2:1.
Bechoros, 26b: It teaches us that to give Matnos Kehunah or Leviyah as payment to Kohanim or Levi?im who assist the owner in the granary or in the abattoir is a desecration which earns Miysah (bi?Yedei Shamayim). 1
Bechoros: As the Navi writes in Mal?achi 2:8 ?Shichatem B?ris ha?Levi?. See also Torah Temimah note 129, who elaborates.
