Chapter 26 of the Book of the Prophet Isaiah, to which the verses you are inquiring about belong, contains a unified poetic work, the "Hymn of Isaiah." It was composed by an unnamed follower of the prophet Isaiah, who lived in the mid-6th century BC and is traditionally referred to as Deutero-Isaiah. This hymn...
Chapter 26 of the Book of the Prophet Isaiah, to which the verses you are inquiring about belong, contains a unified poetic work, the "Hymn of Isaiah." It was composed by an unnamed follower of the prophet Isaiah, who lived in the mid-6th century BC and is traditionally referred to as Deutero-Isaiah. This hymn (which is widely used, incidentally, in Orthodox liturgical worship) is part of a larger text (chapters 24-27), the so-called Apocalypse of Isaiah. Through poetic means, employing historical analogies characteristic of his tumultuous era, Deutero-Isaiah depicts God's impending victory over sin and death. As in other texts by Deutero-Isaiah (who authored the entire second half of the Book of Isaiah, beginning with chapter 40), historical cataclysms here (in particular, the wars between the Persian and Babylonian empires) serve as prefigurations of God's intervention in history. This also applies to the verses in question.
The differences between the texts of the Septuagint and the Vulgate, as well as between the Slavonic and Russian Bibles, can be attributed to the fact that in ancient Israel there were several versions of the text, preserved and transmitted by different groups of scribes. The ancient Hebrew text, preserved in the Masoretic version, was transmitted by the scribes of Jerusalem; the Vulgate follows it, and the Russian Synodal translation was made from it. The Alexandrian Jews preserved and transmitted their own version of the text (perhaps even more than one); the Greek translation (the Septuagint) was made from this version. The Slavonic text was primarily translated from the Greek (especially those passages incorporated into liturgical worship) and was partially (though not entirely) revised according to the Vulgate in the 15th century.
26 A song of praise and confidence in God, for the blessings of righteousness, judgments on their enemies, and favour to his people: their chastisement, repentance, and hope, Isa 26:1-21.
26:9 In the night - When others are sleeping, my thoughts and desires are working towards God. Early - Betimes in the morning. For - And good reason it is that we should thus desire and seek thee in the way of thy judgments, because this is the very design of thy judgments, that men should thereby be awakened to learn and return to their duty; and this is a common effect, that those who have been careless in prosperity, are made wiser and better by afflictions.