申命記 32:46

שימו לבבכם SET YOUR HEARTS [UNTO ALL THE WORDS WHICH I TESTIFY AGAINST YOU THIS DAY] — Indeed, it is necessary for a man that his eyes, his heart and his ears, should all be attentively directed to the words of the Torah, for so it states, (Ezekiel 40:4) “Son of man, behold with thine eyes, and hear with thine ears, and set thine heart [upon all that I shall show thee]” (viz., the plan of the Temple). If in the case of the model of the Temple, which was being made visible to the eyes and was being measured by a rod, it was necessary for a man, according to Scripture, that his eyes, his ears and his heart be attentive, then in order to understand the words of the Torah which are like mountains suspended on a hair (i.e., numerous laws are derived from a single word of the Torah), how much the more is this necessary!

וַיֹּ֤אמֶר אֲלֵהֶם֙ שִׂ֣ימוּ לְבַבְכֶ֔ם לְכׇ֨ל־הַדְּבָרִ֔ים אֲשֶׁ֧ר אָנֹכִ֛י מֵעִ֥יד בָּכֶ֖ם הַיּ֑וֹם אֲשֶׁ֤ר תְּצַוֻּם֙ אֶת־בְּנֵיכֶ֔ם לִשְׁמֹ֣ר לַעֲשׂ֔וֹת אֶת־כׇּל־דִּבְרֵ֖י הַתּוֹרָ֥ה הַזֹּֽאת׃

and he said to them, Set your hearts to all the words which I testify among you this day, which you shall command your children to observe to do, all the words of this Tora.