וזהו שאמרו רז״ל: תרי״ג מצות ניתנו לישראל, בא חבקוק והעמידן על אחת, שנאמר: וצדיק באמונתו יחיה
This is [the meaning of] what our Rabbis, of blessed memory, said:6 “Six hundred and thirteen mitzvot were given to Israel;… came Habakkuk and based them all on a single one – faith as it is written:7 ‘a tzaddik lives by his faith.'”
כלומר: כאלו אינם רק מצוה אחת, היא האמונה לבדה, כי על ידי האמונה לבדה יבא לקיום כל התרי״ג מצות
This means, it is as if they — all the mitzvot — consisted of this one mitzvah of faith alone, for through faith alone one will come to fulfill all the 613 mitzvot.
דהיינו, כשיהיה לבו שש ושמח באמונתו ביחוד ה׳ בתכלית השמחה, כאילו לא היתה עליו רק מצוה זו לבדה, והיא לבדה תכלית בריאתו ובריאת כל העולמות
That is, when his heart will rejoice and be glad with his faith in G‑d’s unity, in perfect joy, as though he were obligated by just this one mitzvah, and it alone were the purpose for which he and all the worlds were created — surely, if there were but one such mitzvah for him to do, he would fulfill it with utmost joy.
הרי בכח וחיות נפשו בשמחה רבה זו תתעלה נפשו למעלה מעלה על כל המונעים קיום כל התרי”ג מצות, מבית ומחוץ
Let him thus rejoice in the mitzvah of faith, and by the power and vitality of his soul [generated] from this great joy, his soul will soar far above all obstacles hindering his fulfillment of all the 613 mitzvot; both [obstacles] from within — from one’s animal soul, and from without — arising from one’s environment.
Being thus imbued with the awareness of G‑d’s true unity, he will be able to overcome any obstacle hindering him from carrying out the mitzvot. For how can anything stand in the path of G‑d’s Will — the mitzvot, when there is nothing in the world apart from G‑d
וזהו שאמר: באמונתו יחיה, יחיה דייקא, כתחיית המתים דרך משל, כך תחיה נפשו בשמחה רבה זו
Thus, the expression יחיה (“will live”) in the verse “a tzaddik will live by his faith” is meant in the sense of “will be revived”; as though resurrected from the dead, so will his soul be revived by this great joy.
והיא שמחה כפולה ומכופלת, כי מלבד שמחת הנפש המשכלת בקרבת ה׳, ודירתו אתו עמו
This is a double and redoubled joy. Apart from the soul’s joy upon apprehending how near G‑d is to him, and how He dwells together with him,
עוד זאת ישמח בכפליים בשמחת ה׳ וגודל נחת רוח לפניו יתברך באמונה זו
he will also rejoice doubly in the joy and pleasure which his faith brings to G‑d.
דאתכפיא סטרא אחרא ממש, ואתהפך חשוכא לנהורא
For thereby, through one’s faith in G‑d’s unity, the sitra achra is truly subdued, and darkness is transformed to light —
שהוא חשך הקליפות שבעולם הזה החומרי, המחשיכים ומכסים על אורו יתברך
meaning the darkness of the kelipot of this corporeal world — which obscure and conceal G‑d’s light
עד עת קץ, כמו שכתוב: קץ שם לחשך
until the End of Days, as it is written,8 “He sets an end to darkness.”
דהיינו קץ הימין, שיעביר רוח הטומאה מן הארץ, ונגלה כבוד ה׳, וראו כל בשר יחדיו, וכמו שכתוב לקמן
(The Biblical phrase, “the End of Days,” is written קץ הימין; ; since ימין (Aram.) means “days” and ימין (Heb.) means “right”, the phrase thus intimates that “in the End of Days G‑d will reveal His right hand” — a reference to His attribute of revelation, when He will banish the spirit of impurity from the earth, and9 “G‑d’s glory, the G‑dliness within every created being, will be revealed, and all flesh together will behold [it].” That is to say, not only the mind, but even the very flesh of man will perceive G‑dliness, as will be explained further.10)
This banishment of the sitra achra will take place only at “the End of Days,” during the Messianic era. Until then, however, while the darkness of kelipah still reigns over the earth, one affords G‑d gratification by crushing the sitra achra and transforming its darkness into light, by means of his faith. And man’s realization of this fact intensifies his own joy in his faith.