Midrash for Numbers 29:1

8) Whence is derive three of three and three (i.e., that he blows three teruoth, each of which is accompanied by a plain blast before and a plain blast after)? From (Vayikra 25:9) "And you shall cause to pass a shofar of teruah," (Vayikra 23:14) "a remembrance of teruah, a holy calling," (Bamidbar 29:1) "A day of teruah shall there be for you."

9) And whence is it derived that what applies to Yovel (vis-à-vis shofar) applies to Rosh Hashanah, and that what applies to Rosh Hashanah applies to Yovel? From the identity (gezeirah shavah) of "in the seventh month" (stated in respect to each).

12 Rabbi Yochanan and Reish Lakish were sitting and having difficulties and saying, "We heave learned [regarding] Rosh Hashanah that comes out to be on Shabbat, we blow in the Temple, but not in the country. If it is the word of the Torah, [blowing the shofar] should override [Shabbat even with]in the borders; if it is not the word of the Torah (but merely rabbinic), it should not override [it] even in the Temple." While they were sitting and having difficulties, Kahana passed by. They said, "The author of the teaching came. Let us go and ask him." They went and asked him. He said to [them], "One Scripture (Leviticus 23:24) states, 'a memorial of blowing'; and another Scripture (Numbers 29:1) states, 'it shall be a day of blowing for you.' How is this? When it comes on Shabbat, it is 'a memorial of blowing.' We mention (remember) [it], but we do not blow." Rabbi Shimon ben Yochai said, "Let it be overridden in the Temple, as they know the time of the new moon (and will be blowing on the right day); but let it not be overridden in the country, as they do not know the time of the new moon." For Rabbi Shimon ben Yochai said, "'It shall be a day of blowing for you. And you shall make a fire-offering' (Numbers 29:1-2) - in the place that they are sacrificing." Rabbi Tachlifa [of] Caesarea said, "In all of the additional offerings, it is written, 'And you shall offer'; but here it is written, 'And you shall make a fire-offering.' How is this? The Holy One, blessed be He, said to Israel, 'My children, I will count it for you as if you were made in front of Me today; as if I created you [as] a new creature today.' This is [the understanding of] that which is written (Isaiah 66:22), 'For as the new heaven and the new earth.'"