Halakhah sa Isaias 1:1: Mishneh Torah, Prayer and the Priestly Blessing, Abudarham, Kitzur Shulchan Arukh & Shulchan Arukh, Orach Chayim

The people have the custom of reading on the three Sabbaths before the Ninth of Ab, as lessons from the Prophets, passages of an admonitory character. On the first of these Sabbaths, the lesson from the Prophets is the section beginning, "The words of Jeremiah" (Jeremiah 1:1-2:3). On the second Sabbath, that beginning, "The vision of Isaiah" (Isaiah 1:1-20). On the third Sabbath, that beginning, "How is the faithful city become a harlot" (ibid. 1:21-2:4).^*Ashkenazi custom is to read respectively on these Sabbaths before the Ninth of Ab, Jeremiah 1:1-2:3, 2:4-28 and Isaiah 1:1-27. On the Sabbath after the Ninth of Ab, the lesson from the Prophets is the section beginning, "Comfort ye, comfort ye, my people" (Isaiah 40:1-26). It is the general custom in our city to read comforting messages from Isaiah as the lessons from the Prophets on the Sabbaths after the Ninth of Ab till the New Year. On the Sabbath between the New Year and the Day of Atonement, the lesson from the Prophets is the section beginning "Return O Israel" (Hosea 14:2-10).

Eleh HaDvarim, before the ninth of Av: Ḥazon Yesha'yahu, Isaiah 1:1–27.

On the three Shabbosos between the seventeenth of Tammuz and Tishah beAv, we read the "Three haftaros of retribution," which are: Divrei Yirmiyahu (The words of Jeremiah) (Jeremiah 1:1), Shim'u devar Hashem, (Hear the word of Hashem) (Jeremiah 2:4), Chazon Yeshayahu, (The vision of Isaiah) (Isaiah 1:1). Their initials form the acronym DeShaCh. If, by mistake, the reader recited on the first Shabbos the haftarah of the weekly portion, on the second Shabbos, he should read the haftarah of both Divrei Yirmiyahu and Shim'u, because they are close to each other. If Rosh Chodesh Av occurs on Shabbos, he reads the haftarah Hashamayim Kis'i (The heaven is My throne) (Isaiah 66), but in some communities, the haftarah Shim'u is read.