The foundation of Elul's character as a time of teshuvah rests on the forty days Moshe ascended Sinai to receive the second Tablets, beginning on Rosh Chodesh Elul and concluding on Yom Kippur — a precedent recorded by the Tur (Orach Chayim 581) and echoed by the Kitzur Shulchan Arukh (128:1), which describes these as days of rachamim and ratzon when teshuvah is especially welcome, and by the Mishnah Berurah (581:1), which derives from the roshei teivot of "אני לדודי ודודי לי" (Shir HaShirim 6:3) both the name Elul and the forty days during which the heart draws near to God and God draws near to accept teshuvah.
The practical avodah of the month, as codified in the Shulchan Arukh (Orach Chayim 581:1–2) and spelled out by the Kitzur Shulchan Arukh (128:2), consists of daily shofar blowing after Shacharit throughout the month and the recitation of Selichot — the shofar serving, as the Kitzur explains, to rouse the people to teshuvah, since it is the nature of the shofar to startle and awaken.
The Mateh Efrayim (581:10–13) gives the month its personal texture: one who fears God should examine his deeds, sit before each meal and before sleep, reckon with his soul to find his wrongdoing, regret it, and confess — adding strength in the fulfillment of mitzvot throughout.
The Rambam's account of what teshuvah actually requires — abandoning the sin, resolving never to return to it, feeling genuine remorse, and verbal confession (Mishneh Torah, Hilkhot Teshuvah 2:2) — extends beyond outward actions: Mishneh Torah, Hilkhot Teshuvah 7:3 stresses that one must also search out bad character traits such as anger, envy, pursuit of money and honor, for these are harder to leave than sins of deed, and Yeshayahu 55:7 is the verse the Rambam anchors this to — "let the wicked abandon his way."
The Hasidic masters deepen the inner dimension: the Shem MiShmuel (Mishpatim 10:14) teaches that in Elul the thirteen attributes of mercy open for Israel and, like water reflecting a face, this divine awakening of love stirs a corresponding awakening of love in the heart of Israel — yet for any supernal light to be retained, one must fashion for it a vessel of mitzvah, which is why the shofar was instituted, to serve as a vessel for that illumination.
The Sefat Emet (Devarim, Elul 12:2) adds that in Elul specifically the revelation of the thirteen attributes of mercy comes through the initiative of Israel — this is the meaning of "אני לדודי," Israel reaching toward God first — while the Sefat Emet (Devarim, Elul 4:2) urges that during these days one must separate from worldly affairs as much as possible in order to fulfill "אני לדודי," remembering that a person was created solely for the service of the Creator.
The Shem MiShmuel (Rosh Hashanah 19:9) reads the Midrash's call to "renew your deeds" in Elul as a directive to see oneself as if born anew today, severing any continuation with past sins, and he teaches that in correspondence with this self-renewal God in His great mercy removes those sins entirely.
The Shem MiShmuel (Shoftim 6:19) frames the entire month as a preparation through yishuv ha-da'at — the settling of the mind — so that one trains oneself to concentrate in prayer and removes all confusion and agitation, since it is through this composed awareness below that the divine attribute of Da'at above is aroused and prosecutorial forces are silenced before Rosh Hashanah.
The Sefat Emet (Devarim, Elul 3:2) situates Elul structurally as the period just before the renewal of the year, when time can receive will and divine influence from the point above time — an "et ratzon" in which even within this world one can cleave to what is beyond it.
The month's suitability for teshuvah is also encoded in its name: the Bnei Yissaschar (Elul 1:1) derives from the final letters of the words in the pasuk "וצדקה תהיה לנו" a gematria pointing to teshuvah, and the Shenei Luchot HaBerit (Rosh HaShanah, Ner Mitzvah 2) adds that the roshei teivot of "ומל ה' אלקיך את לבבך ואת לבב זרעך" (Devarim 30:1) spell Elul — signaling that this month is prepared for the circumcision of the heart.
The Peri Tzadik (Rosh Chodesh Elul 3:3) teaches that Elul was created to repair deeds so that they align with chokhmah, and the Peri Tzadik (Rosh Chodesh Elul 3:4) adds that the forty days of the month serve as preparation to repair what was damaged, corresponding to the giving of the second Tablets with the Oral Torah — making the month an intrinsic preparation for the geulah of Tishrei.
On the inner work of self-assessment, the Mesillat Yesharim (ch. 4) calls for continuous contemplation of the depth of divine judgment and the gravity of one's obligations, noting that one who truly grasps how exacting the reckoning is will naturally shudder and be moved to watchfulness — a disposition central to all serious avodah of this season.
The Tanya (Likkutei Amarim 29:6) prescribes setting aside regular times for genuine humility — meditating deeply, including through study of sacred books, until the heart is truly broken within — while the Tanya (Likkutei Amarim 31:9) balances this by directing that after recognizing one's distance from God, one should turn with compassion toward the divine soul within, which is in a state of exile, as a spur to joyful return rather than despair.
Orot HaTeshuvah describes the most inward dimension of teshuvah as a natural movement of the soul: when a person sins and his soul is not wholly corrupted, the inner sense of uprightness pains him and impels him to return and correct what was wronged until he feels his sin erased — a process that is complex, dependent on many internal and external conditions, but remains one of the essential foundations of teshuvah.
מכתב מאליהו, חלק ב עמוד נו teaches that the entire avodah of Elul is to ignite oneself and greatly increase acts of strengthening — swinging from the extreme of laxity to the extreme of chizuk — and that multiplying mitzvot and their details, even beyond one's normal level, prepares the heart and opens the genuine possibility of teshuvah, for only after the "na'aseh" of many deeds can one arrive at true "nishma."