Here it is known that the holy Torah is referred to as "song," as it is stated (Deuteronomy 31:19): "And now, write for yourselves this song and teach it to the children of Israel; put it in their mouths, so that this song may be a witness for Me against the children of Israel."

In the Gemara (Nedarim 38a), they discuss whether these words were said only regarding the Song of Ha'azinu, and the conclusion of the Gemara is that it refers to the entire Torah. See there where the words of Rabbi Yosei son of Rabbi Hanina are brought, that the Torah was given only to Moses and his descendants, and he acted generously and gave it to Israel. The Gemara questions this: since it is stated, "And now, write for yourselves this song" – the song means the Torah, and all Israel were commanded to write it, so it was given to everyone. The Gemara tries to dismiss this by saying that the words might be referring only to the Song of Ha'azinu. But this is again dismissed based on the latter part of the verse: "so that this song may be a witness for Me against the children of Israel" – if the Song of Ha'azinu was given only to the children of Israel, then what is it witnessing about?

In Tractate Megillah (3a), it brings the words of the angelic commander to Joshua, rebuking him for neglecting the Tamid offering and Torah study. When Joshua asked which of the two he came for, the angelic commander replied: "Now I have come" – and the Tosafot (s.v. 'Now') explain, citing Rivan, that he came for Torah study, as it is written: "And now, write for yourselves this song," end quote.

Indeed, regarding the mitzvah of writing a Sefer Torah, the Rambam wrote (Sefer HaMitzvot, Positive Commandment 18) that only the Song of Ha'azinu is called a song. The commandment to write a Sefer Torah is derived from "And now, write for yourselves this song," meaning that since it is forbidden to write the Torah in sections (Gittin 60a), it necessitates interpreting "this song" to mean the entire Torah, which includes this song. The Ralbag, in his commentary on the Torah, wrote that from what is stated further on: "And Moses wrote this song on that day and taught it to the children of Israel" (verse 22), "And it was when Moses finished writing the words of this Torah in a book until their completion" (verse 24) – it is clear that the song includes all the words of the Torah until their completion.

Indeed, even the Rambam himself referred to the Torah as "song" in his writings in the Yad HaChazakah. In his words (Chapter 3 of the Laws of Torah Study, Halacha 13), even though it is a mitzvah to study both day and night, a person learns most of his wisdom at night. Therefore, one who wants to merit the crown of Torah should be careful with all his nights and not waste even one of them in sleep, eating, drinking, talking, or similar matters, but rather in Torah study and words of wisdom. The Sages said: There is no song of Torah except at night, as it is stated (Lamentations 2:19): "Arise, cry out in the night." And anyone who occupies himself with Torah at night, a thread of kindness is extended over him during the day, as it is stated (Psalms 42:9): "By day the Lord will command His lovingkindness, and in the night His song shall be with me, a prayer to the God of my life," etc., end quote.

Further, we find in the Gemara (Berachot 6a) the following statement: It was taught, Abba Binyamin says, a person's prayer is only heard in a synagogue, as it is stated (1 Kings 8:28), "To hear the song and the prayer" – in the place of song, there shall be prayer. And in Rashi (s.v. 'in the place'), this is his language: in the place of song – in the synagogue, where the congregation says songs and praises with a pleasant voice, end quote. However, the halacha is ruled (Shulchan Aruch, Orach Chaim, Siman 90, Se'if 18): "A fixed study hall is holier than a synagogue, and it is a mitzvah to pray there rather than in a synagogue." This raises the question, why, since the synagogue is the place of song. Indeed, the study hall is also a place of song – the song of Torah, as the Rambam wrote, and therefore, since its holiness is greater than that of the synagogue, it is preferable to pray there.

All this aligns well with our discussion about the song, which fills a person's soul with the immense joy of recognizing the truth of His existence and cleaving to Him and His holy spirit, until it overflows and 'pours out' in a great outpouring of song and praise – and this is indeed the holy Torah, its essence and subject, for there is no greater cleaving to the Creator and the truth of His existence than through pure Torah study. Therefore, it is fitting that the Torah is called 'song.'

And this is the language of the great Rabbi Aharon Kotler zt"l (Mishnas Rabbi Aharon, Parshas Beshalach, Inyan Hashira), what one attains in Torah is considered as seeing the spiritual reality, as it is written (Ecclesiastes 1:16) "and my heart has seen much wisdom and knowledge." For the Torah is the connection between the Holy One, blessed be He, and Israel, and all the worlds, and through the Torah, a vision is renewed in the spiritual world that brings about song and praise. And thus, indeed, the study of Torah should be, with the elevation of the soul and the dedication of all senses and feelings, end quote. See there further.