The focus of the third perek of Massekhet Rosh HaShana is the mitzva of sounding the shofar on the holiday. The commandment is mentioned twice in the Torah (see Vayikra 23:24 and Bamidbar 29:1), but only in the most general terms. This perek offers the details that are essential to fulfilling the mitzva properly, including such questions as:
What is the instrument that is blown?
- What is it made out of?
- How is it fashioned?
- How large must it be?
- Does it have to be a particular shape?
The other central question is:
- How is the instrument to be blown?
- Will any sounds do, or are there specific ones that must be made?
- Is there a particular order to the sounds?
- Is there a specific number of sounds required?
The Mishna teaches that all shofarot can be used on Rosh HaShana, except for that of a cow, since a cow has a keren – horn – rather than a shofar. Rabbi Yosei permits the use of a cow’s horn, arguing that all shofarot are referred to as keren (see Yehoshua 6:5).
Although the Mishna very specifically teaches the reasoning behind the two opinions on the use of the horn of a cow, two amora’im nevertheless suggest alternative explanations for the disagreement.
Abaye says that the basic position in the Mishna stems from the Biblical requirement of a single shofar – not two or three shofarot. The horn of a cow is made up of several layers, so it cannot be used (Rabbi Yosei argues that we see the layers as making up a single shofar).
Ulla suggests that the basic position of the Mishna is based on the rule en kategor na’aseh sanegor – a prosecuting attorney cannot become a defense attorney. Just like the High Priest cannot wear his gold garments into the Holy of Holies when performing the Yom Kippur service, similarly the horn of a cow cannot be used to call out in defense of the Jewish People. Rashi explains that the cow invokes the Golden Calf and therefore is considered a member of the prosecution. In general, gold is seen as representing vanity and a desire for material wealth, which do not seem appropriate for prayers of forgiveness.