שׂ֧וֹשׂ אָשִׂ֣ישׂ בַּֽיהוָ֗ה תָּגֵ֤ל נַפְשִׁי֙ בֵּֽאלֹהַ֔י כִּ֤י הִלְבִּישַׁ֙נִי֙ בִּגְדֵי־יֶ֔שַׁע מְעִ֥יל צְדָקָ֖ה יְעָטָ֑נִי כֶּֽחָתָן֙ יְכַהֵ֣ן פְּאֵ֔ר וְכַכַּלָּ֖ה תַּעְדֶּ֥ה כֵלֶֽיהָ׃
Aku akan sangat bersukacita karena Yang Mahakekal, jiwaku akan bersorak-sorai karena Allahku; sebab Ia telah mengenakan kepadaku pakaian kelepasan, Ia telah menyelubungi aku dengan jubah kebenaran, seperti pengantin laki-laki yang mengenakan hiasan kepala yang megah bagaikan seorang imam, dan seperti pengantin perempuan yang berhias dengan perhiasannya.
Abudarham
Atem Nitsavim, before Rosh haShanah: Sos Asis, Isaiah 61:10–63:9.
Abudarham
And the Midrash punningly says that they established to say at the beginning of the prophetic readings of consolation "Comfort, comfort my people" (Isaiah 40:1) — that is to say, the Holy Blessed One said to the prophets, "Comfort, comfort my people!" Upon this the congregation of Israel responds, "But Zion says, 'the LORD has abandoned me!'" (Isaiah 49:14) that is to say, "I cannot be reconciled to the comfort of the prophets." And it says "Rise, rise, dress in strength, arm of the LORD; rise as days of old!" (Isaiah 51:9). And in places where it they conclude in place of this prophetic reading "Unhappy, storm-tossed" (Isaiah 54:11), it is as if to say the prophets respond and say before the Holy Blessed One, "Lo, the congregation of Israel is not reconciled to our comforting!" Upon this the Holy Blessed One responds and says, "I, I myself will comfort you" (Isaiah 51:12), and what's more, "Rejoice, barren one without children" (Isaiah 54:1), and what's more, "Rise, shine, for your light has come!" (Isaiah 60:1). To this, the congregation of Israel responds, "I will rejoice, rejoicing in the LORD" (Isaiah 61:10), that is to say, now I have something to rejoice and celebrate! "My soul will cheer in my God, who clad me in clothing of salvation" etc.
Shulchan Arukh, Orach Chayim
The custom on a Shabbos where a groom is present is to recite after the haftarah of (The word "haftarah": some say it is [related to] the phrase ain maftirin achar ha-pesach ["We do not eat anything after the [korban] pesach"], meaning, remove [it] [i.e. which signals the end]; that is to say, it is the removal/ending of the morning prayers) that week, two or three verses from the haftarah of "Sos Asis" ["I greatly rejoice" - Isaiah 61:10]. And when Rosh Chodesh falls out on Shabbat and Sunday, after we recite the haftarah for that Shabbat, we recite the first verse and the last verse of the haftarah of "Va-yomer Lo Yehonatan, machar chodesh" ["And Yehonatan said to him 'tomorrow will be the new moon'" - Samuel 20:18]. And one should not protest [this custom]. [And see below in siman 425, se'if 3, and the end of siman 428 for how we [Ashkenazim] practice.]