Rosh Hashana 3:8-4:1
Rosh Hashana 3:8
(The previous mishna discussed having the intention to fulfill the mitzvah. The Mishna here discusses the idea of intentions.) Regarding the war with Amalek, Exodus 17:11 says, "When Moshe raised his hand, Israel prevailed… ” Did Moshe’s hands cause success or failure in battle? Rather, we learn from this that when the Jews would look up and submit themselves to God, they would prevail; if not for that, they would be defeated. Similarly, Numbers 21:8 instructs Moshe to make an image of a snake and to place it on a pole so that anyone bitten by a snake who sees it will live. Does a snake kill or heal a person? Rather, when the Jews would look up and submit themselves to God, they would be healed. If not for that, they would be harmed. (Having concluded the tangent about intentions, the Mishna now returns to the topic of Rosh Hashana.) A person with congenital deafness, a mentally-incompetent person and a minor cannot perform an obligation for others. The general rule is that anyone who is not obligated in a matter cannot perform it on behalf of others (who are so obligated).
Rosh Hashana 4:1
When Rosh Hashana fell on Shabbos they would blow shofar in the Temple but not elsewhere. After the Temple was destroyed, Rabbi Yochanan ben Zakkai instituted that the shofar be blown in any location that has a court. Rabbi Eliezer said that this was only instituted for Yavneh but the Sages maintained that it applied to any other location with a court.