Those who say Tehillim continuously for forty days as a segulah (spiritual remedy) and missed one day may complete the reading on the following day.
Sources and Explanations
See what is cited in the name of Rav Elyashiv zt”l in the sefer Ashrei HaIsh (Orach Chaim vol. 3, chapter 71, ot 22). And see what the Mishnah Berurah (554:7) cites: those who are accustomed to say Tehillim and Shir HaYichud at Minchah should not say it on Tisha B’Av, and in the city of Posen the custom is to say on the following day the chapters of the previous day and those of that day.
Also the sefer Mateh Efraim (siman 602, se’if 20) writes similarly: “On the Fast of Gedaliah they begin saying Tehillim before the amud (prayer stand), and they say it on all the days between Rosh Hashanah and Erev Yom Kippur except for Shabbat, which are five days, each day one book or three kapitel (chapters). And whoever did not say it on one day should complete it on his own on the following day, in order to finish all of Tehillim before Erev Yom Kippur.”
And the sefer HaShakdan (about Rav Yosef Shalom Elyashiv zt”l) writes that this segulah of reading for forty consecutive days is a new invention, and one should not establish halachot regarding such matters. Therefore, it seems that one who does wish to read should not worry that if he lost his continuity he has also lost the segulah he is hoping for.
Indeed, although we have not found a segulah in the words of Chazal, we have found the concept of a prayer of forty days, namely in Midrash Rabbah, Va’etchanan (chapter 2, 17), which states: “The Rabbis said: There is a prayer that is answered after forty days. From whom do you learn this? From Moshe, as it is written: ‘And I fell down before Hashem forty days’” etc.
From the sefer “Shaf Veyativ – Laws of Saying Tehillim” by Rabbi Shay Tahan, Chapter 1: The Virtues and Merits of Saying Tehillim, Halacha 8 (p. 12 in the print edition). Translated from the Hebrew original.
