From Elul to Sh’mini Atzeres: The Ashkenazic Minhag to Recite L’Dovid, Hashem ‘Ori v’Yish’i

Hashem ‘Ori – God is my light. The custom to say this mizmor during the period of teshuvah is based on the Midrash Shochar Tov (Minhagei Yeshurun, 139):

God is my light, on Rosh Hashanah; my salvation, on Yom Kippur; ki yitz’pe’neni b’sukoh, He will hide me in His shelter, an allusion to Sukkos.

The implication is that on Rosh Hashanah God helps us to see the light and repent, on Yom Kippur He provides us salvation by forgiving our sins. Once we are forgiven, He shelters us from all foes and dangers, just as He sheltered our ancestors in the Wilderness. Because of this allusion to the preparation for repentance and its aftermath, the custom was adopted to recite this mizmor during the entire repentance period from Rosh Chodesh Elul through Sh’mini Atzeres.

Another allusion to Elul in the mizmor is the word, lu’le, which is Elul spelled backwards.

Minhag Not Accepted by All
Ostraha, a city in Volhynia, Ukraine, famous since the 16th century because it was served by gedolim, such as, Maharshal, the Shelah, Maharsha and the Taz, kept a record of customs.
According to the Minhagei Beis Ha’knesses Ha’Gadol of Ostraha, every day the shir shel yom was said before birkos ha’shachar. At the conclusion of shacharis, no mizmorim were said, even the mizmor, l’dovid ‘ori v’yish’i, in the months of Elul and Tishrei. The exception to the rule was during ‘aseres y’mei teshuvah when the entire Sefer Tehillim was recited.

The Aderes, R. Eliyahu Dovid Rabinowitz Se’omin of Mir, Ponivezh and Jerusalem, comments on the minhag in Ostraha to exclude l’dovid ‘ori:

The Gra (Ma’aseh Rav 53) held, like other later ge’onim (unnamed), that the mizmor, l’dovid ‘ori, is not said. The general reasons given are aversion to placing an undue burden on the community, torach tzibur (Berakhos 13b) and because it keeps people from getting to work (Megillah 21a).
--Sefer Tefilas Dovid, (Ahavas Shalom edition, Jerusalem, 2004), pp.140-141n.

Mishnah Berurah Mentions the Prevalence of the Minhag
The Mishnah Berurah (581:2) says that the prevalent custom in his parts was to recite the mizmor, l’dovid ‘ori after davening, morning and evening, up to and including Sh’mini ‘Atzeres.

Hidden Meaning Explored in Derush
This minhag was the topic of a derashah (Ya’aros Devash, Part I: Derush 11) by R. Yonasan Eybeshutz. He explains some of the hidden meaning behind this mizmor.

The Gemara in Yoma (20a) says:
Satan has no permission to act as accuser on the Day of Atonement. Whence [is that derived]? — Rama b. Hama said: HaSaTaN in numerical value (5+300+9+50) is three hundred and sixty-four, that means: on three hundred and sixty-four days he has permission to act as accuser, but on the Day of Atonement he has no permission to act as accuser.

It is written: And ye shall afflict your souls, in the ninth day of the month at evening. Now, do we fast on the ninth? Why, we fast on the tenth! But this teaches you that if one eats and drinks on the ninth, Scripture accounts it to him as if he fasted on the ninth and tenth. (Berakhos 8b)

The two days of Rosh Hashanah are considered one long day, yoma arichta. Adam was created on Erev Shabbos, the first of Tishrei. The Midrash says, the sun did not set the entire day of Shabbos until the conclusion of Shabbos. Then Adam thought the world was darkness. Therefore, the first and second day of Tishrei was one long day.

As the Midrash says:
R. Levi said in the name of the son of Nezirah: That light functioned thirty-six hours, twelve on the eve of the Sabbath [i.e. Friday], twelve during the night of the Sabbath, and twelve on the Sabbath [day]. When the sun sank at the termination of the Sabbath, darkness began to set in. Adam was terrified, [thinking,] Surely indeed the darkness shall bruise [E.V. ’envelop’] me (Ps. CXXXIX, 11): shall he of whom it was written, He shall bruise thy head (Gen. III, 15) now come to attack me! What did the Lord do for him? He made him find two flints which he struck against each other; light came forth and he uttered a blessing over it; hence it is written, But the night was light about me-ba'adeni (Ps. loc. cit.), i.e. the night was light in my Eden (be-’edni). (Bereishis Rabbah 12:6)

Therefore, in the year the world was created Yom Kippur was on the ninth of Tishrei, based on the solar days. Hence the pasuk: v’e’nisem ‘es naf’sho’sei’khem b’tish’ah la’chodesh ba’erev…, you shall afflict your souls; in the ninth day of the month at evening….

But according to the lunar days, it was the tenth day. Because the first two days were indeed two days.

When the world was created Satan was given power over 364 days of the year in solar days. In fact, to this day the Western world uses the solar calendar. Satan in gematria is 364. Yom Kippur is not included because Rosh Hashanah is divided into two days. That is how Yom Kippur became the tenth day. Satan has no dominion over that day because it is beyond 364. The first year of creation only had 364 days. Yom Kippur is one day, separate and unique. The beginning of the next cycle of 10 in the decimal system.

Based on the Midrash (Bereishis Rabbah 82:3), Yom Kippur is a special day separate, distinct and different from all the other days of the year. On the ninth one may eat because Satan has dominion over it. Satan has a share in the eating because it is part of the material world, gashmiyus. However, Satan has no dominion over the tenth, because it is completely holy to God. Yom Kippur is the Yom HaKadosh, par excellence. This Holy Day is the day on which there is salvation and help, yesh’a and ‘ozer, because Satan has no dominion over that day.

Hence, Rosh Hashanah is ‘ori, my light, because it is a long day with plentiful light for two days in one without any darkness. Because of that long day at the time of creation, God is my salvation, Hashem yish’i, on Yom Kippur. There is no Satan to interfere on that day of Yom Kippur which is beyond the 364 days of the solar year. Rather, Hashem is our salvation on Yom Kippur and we receive atonement.