Much of the Temple service involves collecting parts of sacrifices in a keli sharet – a special Temple vessel – an act that sanctifies that part of the offering and prepares it for its intended use as part of the service.
The Mishnah on today’s daf (=page) rules that if the kometz – the fistful of flour removed by the kohen from the meal-offering for sacrifice on the altar – was not placed in a keli sharet, it is invalid. Rabbi Shimon disagrees, ruling that it remains valid nevertheless.
Rashi explains that according to all opinions, the original meal-offering must be brought in a keli sharet in order to sanctify it in the first place. The disagreement focuses only on the second stage, when the kometz is taken from the meal-offering, when it is placed in another keli sharet to be sanctified for placement on the altar. Nevertheless, from the Rambam‘sCommentary to the Mishnah it appears that he views the disagreement even in the first stage of preparation.
In explaining Rabbi Shimon’s position, Rabbi Yehudah the son of Rabbi Hiyya points to a passage (Sefer Vayikra 6:10) that compares the minhah – the meal-offering – to both a hatat – a sin-offering – and an asham – a guilt-offering. Thus, if someone chooses to perform the service of the minhah following the model of a hatat, he does it with his right hand, like the hatat, whose blood is sprinkled on the altar by the kohen using his right hand. He can also choose to perform the service of the minhah following the model of an asham, whose blood is poured on the altar from a keli sharet even with the left hand.
One way of understanding this explanation is that since Rabbi Shimon allows the service to be performed by hand, he never actually requires a keli sharet for this service. A second approach is to say that Rabbi Shimon offers two possible methods of performing this service – either by hand or with a keli sharet. According to this last approach, when the Mishnah quotes Rabbi Shimon as allowing the meal-offering to be brought without a keli sharet, that would only be true if it was done with the right hand.