The Mishnah on Blowing the Shofar

3:2. All horns may be used except for that of a cow, because it is [called] a keren. R. Yosi said: Are not all horns called keren, as it says: When they make a long blast with the ram’s horn [keren], [when you hear the sound of the horn (shofar)]? (Joshua 6:5).¹

3. The horn [shofar] used on Rosh Hashanah was that of an ibex, straight, and its mouth was overlaid with gold. There were two trumpets, one on each side of it. The horn gave a long blast and the trumpets a short one, since the commandment of the day was with the horn. [ . . . ]

4:1. If the festival day of Rosh Hashanah fell on the Sabbath, they would blow the horn in the Temple but not in the country. After the destruction of the Temple, R. Yoḥanan ben Zakkai decreed that it should be blown [on the Sabbath] in every place where there was a court. R. Eliezer said: R. Yoḥanan ben Zakkai decreed for Yavneh only. They said to him: Both Yavneh and any place where there is a court. [ . . . ]

9. The order of the blasts: three sets of three each. The length of a teki‘ah is equal to three teru‘ot, and the length of a teru‘ah is equal to three yevavot. If one prolonged the first teki‘ah so that it went directly into the second, it counts only as one. One who has blessed [recited the Amidah] and then a shofar is given to him, he sounds a teki‘ah teru‘ah teki‘ah three times.