Talmud Bavli Menachot on the Mitzvah to Write a Torah Scroll

"And Rabbi Yehoshua bar Abba said in the name of Rav Gidel, who said in the name of Rav: One who buys a Torah scroll from the market is like on who grabs a mitzvah from the market.  If he wrote it himself, Scripture considers him as if he received it personally from Mount Sinai."

-- Talmud Bavli, Menachot 30a

"And now write for yourselves this song, and teach it to the Children of Israel, place it in their mouths."

-- Deuteronomy 31:19

Rabbi Moshe Cordovero on the Letters of Emanation and Performing Mitzvot

"There is no doubt that the letters that compose each and every pericope of the Torah, and every Gemara and chapter someone is studying, which concern a certain Mizvah, have a spiritual reality which ascends and clings to the branches of a certain sefirah, namely the sefirah that hints to this Mizvah, and when the person studies the corresponding Mizvah or the chapter or the pericope or the verse, those letters will move and stir on high.

"And behold, the voices and the realities of the letters produced by the twist of the lips bestow on them a certain act and movement like that of a body. And the reality of the letters ascends and it is found everywhere on the way of their ascent from one aspect to another, following the way of the descending emanation from one stage to another."

-- Rabbi Moshe Cordovero, Or Yaqar vol. 12 p. 147 (transl. Idel in "Reification of Language in Jewish Mysticism" 1992)