Leviticus 23
23 The Lord said to Moses,
24 “Say to the Israelites: ‘On the first day of the seventh month you are to have a day of sabbath rest, a sacred assembly commemorated with trumpet blasts.
25 Do no regular work, but present a food offering to the Lord.’”
Numbers 29:1-6
1 “‘On the first day of the seventh month hold a sacred assembly and do no regular work. It is a day for you to sound the trumpets.
2 As an aroma pleasing to the LORD, offer a burnt offering of one young bull, one ram and seven male lambs a year old, all without defect.
3 With the bull offer a grain offering of three-tenths of an ephah of the finest flour mixed with olive oil; with the ram, two-tenths;
4 and with each of the seven lambs, one-tenth.
5 Include one male goat as a sin offering to make atonement for you.
6 These are in addition to the monthly and daily burnt offerings with their grain offerings and drink offerings as specified. They are food offerings presented to the LORD, a pleasing aroma.
Jubilees 6:23-26
And on the new head of the first month, and on the new head of the fourth month, and on the new head of the seventh month, and on the new head of the tenth month are the days of remembrance, and the days of the seasons in the four divisions of the year. These are written and ordained as a testimony for ever. And Noah ordained them for himself as feasts for the generations for ever, so that they have become thereby a memorial unto him. (…) And on the new head of the seventh month all the mouths of the abysses of the earth were opened, and the waters began to descend into them.
Jubilees 5:29-30
And (on the head) in the fourth month the fountains of the great deep were closed and the flood-gates of heaven were restrained; and on the head of the seventh month all the mouths of the abysses of the earth were opened, and the water began to descend into the deep below. And on the head of the tenth month the tops of the mountains were seen, and on the head of the first month the earth became visible.
Temple Scrolls
XXV (…) In the [seventh] m[onth, on the first day of the month, you shall have] a sacred rest, a remembrance announced by a trumpet blast, a [holy] ga[thering. You shall offer a holocaust, an offering by fire, of soothing odour be]fore YHWH. You shall o[ffer on]e [young bull,] one ram, seve[n] ye[ar]ling [lamb]s [without blemish and one he-goat for a sinoffering, and] the corresponding grain-offering and drink-offering according to the statute concerning the[m, of soothing odour to YHWH, in addition to] the perpetual [holocaus]t [and the holo]caust of the new moon month (chodesh?). Afterwards [you shall offer] this [holocaust] at the third part of the day, an eternal rule for your generation[s wherever you dwell.] You shall rejoice on this day. On it you shall do no work. A sacred rest shall this day be for you.
Abraham:
Jubilees 12:16-18
And in the sixth week, in the fifth year thereof, Abram sat up throughout the night on the head of the seventh month to observe the stars from the evening to the morning, in order to see what would be the character of the year with regard to the rains, and he was alone as he sat and observed. And a word came into his heart and he said: All the signs of the stars, and the signs of the moon and of the sun are all in the hand of the Lord. Why do I search (them) out? If He desires, He causes it to rain, morning and evening; And if He desires, He withholds it, And all things are in his hand.’
Also see: What is the Feast of Trumpets?