Sefat Emet - on Kedoshim (1871) supra. "In the midrash..."
In the midrash on "And when you come into the land, and shall have planted all manner of trees for food, etc." (Lev, 19:23), they mention "It's a tree of life for those who hold fast to it" (Prov, 3:18), as it is written: "And gave us a Torah of truth and eternal life planted [within us]" (Torah blessings). "Torah of truth" refers to the Written Torah. And the Oral Torah is [what God] "planted among us" to bring internal life force to our forgetfulness by means of study/labor, as it is written: "Her breasts will sate you at all times" (Prov, 5:19), for he will always find flavor (ta'amim) in Torah. That that's why it is written: "To those who hold fast to it, etc." since even someone who is occupied with [the work of] this world--in any case his will will be fixed and planted in Torah.
(א) וכי תבואו אל הארץ ונטעתם כל עץ מאכל - הדא הוא דכתיב (משלי ג): עץ חיים היא למחזיקים בה...
רב הונא בשם ר' בנימין בן לוי אמר: משל למלך, שאמר לבנו: צא לפרקמטיא! אמר לו: אבא מתיירא אני בדרך מהלסטים ובים מפני אפורטין. מה עשה אביו? נטל מקל וחקקו ונתן בו קמיע ונתנה לבנו ואמר לו: יהי המקל הזה בידך ואי אתה מתיירא משום בריה. אף כך אמר הקב"ה למשה: אמור לישראל: בני! עסקו בתורה ואין אתם מתייראים משום אומה. אילו נאמר: עץ חיים היא לעמלים בה לא היתה תקומה לשונאי ישראל, אלא למחזיקים.
Chapter XXV (KEDOSHIM)
I. AND WHEN YE SHALL COME INTO THE LAND, AND SHALL HAVE PLANTED ALL MANNER OF TREES FOR FOOD (XIX, 23). This bears on the text, She is a tree of life to them that lay hold upon her (Prov. III, 18)....
R. Huna in the name of R. Benjamin b. Levi said: The matter may be compared to the case of a king who said to his son: 'Go out and do business.' Said the son to him: 'Father, I am afraid of robbers on the road and of pirates on the sea,' What did his father do? He took a staff, hollowed it out and placed an amulet inside it. He gave it to his son and said to him: 'Let this staff be in your hand and you need not be afraid of any creature.' So also did the Holy One, blessed be He, say to Moses: 'Tell Israel: "My children! Occupy yourselves with the Torah and you need not be afraid of any nation."' If the text had read, 'She is a tree of life to them that toil in her' Israel's enemies [i.e., Israel] would have been unable to survive. What it says therefore is not that, but: ‘To them that lay hold upon her.’
בָּרוּךְ אַתָּה ה' אֱלהֵינוּ מֶלֶךְ הָעולָם. אֲשֶׁר נָתַן לָנוּ תּורַת אֱמֶת וְחַיֵּי עולָם נָטַע בְּתוכֵנוּ. בָּרוּךְ אַתָּה ה', נותֵן הַתּורָה:
Blessed are you, Hashem our God, sovereign of the universe, who gave us a Torah of truth and planted within us eternal life. Blessed are you, Hashem, giver of the Torah.