Midrasch zu Megillah 4:14

For this mitzvah (Deuteronomy 30:11) - Halacha: a person in Israel that stands to read from the Torah, how does that person bless? This is what the sages taught: the one who begins and the one who ends say a blessing before and after the Torah (Mishnah Megillah 4:2). And from where do we know that [reading the Torah] needs a blessing before and after? As it is written " Blessed are You, Ad-nai; train me in Your laws. " (Psalms 119:12) - here is the blessing before. And from where do we know that [reading the Torah] needs a blessing after? Rabbi Shmuel bar Nachman said in the name of Rabbi Yonatan: it is written after the song (Deuteronomy 33:1) "and this is the blessing - [so too] one who taught Torah to them and afterwards blessed: here is the blessing afterwards. Another explanation: the Holy Blessed One said "if you merited to bless the Torah, I too will bless you, as it is written "in every place you call My name, I will come to you and bless you" (Exodus 20:21). The rabbis said another explanation: the Holy Blessed One said: if you bless the Torah, you bless your own self. From where [do they know this?] "For through me your days will increase, and years be added to your life" (Proverbs 9:11). And if you say that I gave the Torah to you for your detriment, that is not true, I only gave Torah to you for your benefit since the ministering angels desired Torah and it was hidden from them, as it says, "She has been hidden from the eyes of all living," (Job 28:21) these are the animals, "and from the birds of the sky it has been hidden," these are the angels. How do we know this? As it says, "One of the serafim (type of angel) flew to me," (Isaiah 6:6) God said to Israel: My children! From the ministering angels this thing is out of reach, but from you it is not. From where do we know this? From what is written regarding this issue: "this mitzvah which I enjoin upon you this day is not too baffling for you, nor is it beyond reach" (Deuteronomy 30:11).

The intercalation takes place in the presence of three; Rabbi Eliezer says that ten (men are required), as it is said, "God standeth in the congregation of God" (Ps. 82:1), and if they become less than ten, since they are diminished they place a scroll of the Torah before them, and they are seated in a circle in the court-room, and the greatest (among them) sits first, and the least sits last; and they direct their gaze downwards to the earth and (then) they stand and spread out their hands before their Father who is in heaven, and the chief of the assembly proclaims the name (of God), and they hear a Bath Ḳol (saying) the following words, "And the Lord spake unto Moses and Aaron… saying, This month shall be unto you" (Ex. 12:1, 2).