The Mishna Berurah (סימן תקפ”א ס”ק ג’) brings from the מטה אפרים the minhag to say b’tzibbur ten mizmorim of Tehillim every weekday of Elul. By doing so, one will finish sefer Tehillim twice during Elul. There are one hundred and fifty mizmorim of Tehillim, and when recited twice equals three hundred, which is the numerical value of the word כפר. The יסוד ושורש העבודה writes that it is a known segula, that the reciting of Tehillim brings כפרת עונות. The אלף המגן brings from the ספרים הקדושים that one who is accustomed to saying Tehillim – דוחה כל מיני פורעניות ופגעים רעים מעליו ובני ביתו ומשפחתו וכל בני דורו, ומגלגל עליו ועליהם כל מיני שפע ברכות טובות והצלחות ורחמים וחסדים – he holds back punishments and terrible things from himself, his family, and his entire generation, and brings upon them brocha, success, mercy and kindness.
Which day do we start reciting the Tehillim? The Mishna Berurah (סימן תקפ”א ס”ק א’) says that on Rosh Chodesh itself אין אומרים סליחות ותחנונים. Therefore, those who have the minhag to say Tehillim every day during Elul together with the יהי רצון afterwards, which includes the י”ג מדות, should only start saying the Tehillim after Rosh Chodesh on ב’ אלול. Since one is not saying the entire Tehillim every day the proper nusach to say is בזכות מזמורי תהלים שקראנו לפניך. If one does not say the יהי רצון afterwards, then he should start on Rosh Chodesh Elul itself which is the last day of Av.
As mentioned earlier the minhag is to say it בציבור. For some unknown reason this minhag is not practiced in many places. When the חזון אי”ש was asked about this minhag he answered ודאי – meaning yes, this is the minhag. Reb Chaim Kanievsky shlit”a writes, that he says it in shul by himself. He also writes that if it won’t cause machlokes one should try to make sure this minhag is done in his shul בציבור. The מנהג הישיבות is not to say it. Some say the reason is because of ביטול תורה. Instead they add time onto the mussar seder. Reb Shmuel Kamenetzky shlit”a says that if one who has the minhag to say it b’tzibbur finds himself in a place where they don’t say it, he should say it ביחידות. When saying it b’tzibbur, kaddish is recited afterwards. If there is no minyan during the Tehillim and they are waiting for a minyan to say kaddish they should say the last kapittel when there is a minyan and then say kaddish.
לכתחילה even during Elul, one should not say Tehillim at night.
The מטה אפרים says that during עשרת ימי תשובה one should finish sefer Tehillim a third time.1
Prepared by R’ Avrohom Yehoshua Ziskind
1Sources:האלולים קודש לה’,קובץ הלכות,אני לדודי