I found online that Teshuvah stands for:
תמים תהיה עם ה' אלקיך
שויתי ה' לנגדי תמיד
ואהבת לרעך כמוך
בכל דרכיך דעהו
הצנע לכת עם אלוהיך
Is there any source for this?
Hayom Yom, 3 Tishrei
The Tzemach Tzedek had yechidus with the Alter Rebbe on Monday of Teitzei, 6 Elul 5564 (1804); the Rebbe told him: "On Shabbat Tavo 5528 (1768), my Rebbe (the Maggid of Mezritch) said a "Torah" beginning V'shavta ad Havayeh Elokecha1 He explained that the avoda of teshuva must attain a level at which Havayeh, transcendent Divinity beyond worlds, becomes Elokecha - Elokim being numerically equivalent to hateva (nature), and as we find, "in the beginning Elokim created the heavens and the earth etc." All the Holy Society (disciples of the Maggid) were profoundly stirred by this teaching. The tzadik R. Meshulam Zusya of Anipoli said that he could not attain the heights of such a teshuva; he would therefore break down teshuva to its components, for each letter of the word teshuva is the initial of a verse:
T: Tamim - "Be sincere with the Eternal your G-d."
Sh: Shiviti - "I have set G-d before me always."
U: V'ahavta - "Love your fellow as yourself."
V: B'chol - "In all your ways, know Him."
H: Hatznei'a - "Walk discreetly with your G-d."
When my father told me this, he concluded: "The word teshuva comprises five (Hebrew) letters, each letter a path and a method in the avoda of teshuva." (He explained each method at length). Each moves from a potential state to actuality through the avoda of davening.
Hayom Yom, 4 - 8 of Tishre:
T: Tamim..., "Be sincere with G-d." This represents the avoda of teshuva that comes through sincerity. Sincerity, or "wholeness," takes any number of forms and has many levels. In reference to teshuva the highest form is wholeness of heart - called "earnestness"; as Torah says of Avraham, "you found his heart faithful before You."
Sh: - Shiviti..., "I have set G-d (Havayeh) before me always." Havayeh indicates the creation of the universe and creatures. Bringing all of Creation into being and sustaining it is accomplished by bridging an infinite gap - from ayin (non-being, nihilo) to yesh (being). This form of the avoda (service) of teshuva results from one's constant awareness2 of the way in which the universe and all that is in it, is (constantly) brought into being.
U - V'ahavta..., "Love your fellow as yourself." The Alter Rebbe taught that this love is an instrument, a means to "Love the Eternal your G-d." This is explained in the statement, "Whoever is pleasing to man is pleasing to G-d." This service of teshuva stems from goodness of heart.
V - B'chol..., "In all your ways, know Him." A person who sets his heart and mind to observe all that happens to him and around him, will perceive G-dliness tangibly in evidence; as the Mitteler Rebbe pointed out, men of affairs have an advantage over secluded scholars, in that the former can witness actual manifestations of G-dliness. This form of the service of teshuva comes from one's perceiving hashgacha p'ratit, (particular Divine Providence).
H - Hatznei'a..., "Walk discreetly with your G-d,". One must take care not to be conspicuous or ostentatious in the slightest. It is said "Man should always be artful in piety." The artfulness lies in seeing that his piety not be noticed at all. We know that a number of the early chassidim concealed their true selves, and when discovered were sincerely distressed. This is the avoda of teshuva that comes from hatznei'a lechet, being discreet.