In those days: that is, “at that time.” This presumably refers to the time established at the beginning of the chapter.

I, Daniel: see 7.15, 28; 8.1, 15, 27.

Mourning: this term does not indicate that one of Daniel’s close relatives had died. Among the Jewish people mourning rituals were practiced, not only at the death of a relative, but also during times of national crisis. The same rituals were sometimes performed with the purpose of showing repentance and asking God to pardon national sins (see 9.3), or as a kind of spiritual preparation to receive a revelation from God (compare Exo 34.28). A more detailed explanation of what the mourning practices were is given in the following verse. Here it seems that Daniel’s actions were intended to prepare himself for the understanding of God’s revelation. Some other translations of this verb are “doing … penance” (New Jerusalem Bible), “afflicted myself” (Anchor Bible) and “had been very sad” (New Century Version). In those languages where the verb “mourn” is used exclusively of the action that follows the death of relatives or close friends, another verb should be chosen.

For three weeks: literally “three weeks of days.” The added information “of days” in Hebrew is important in the overall context of the Book of Daniel. In contrast with the “weeks of years” in chapter 9, here it is ordinary seven-day weeks that are intended. Further, this precision shows that it was not “approximately three weeks” but precisely three full weeks or twenty-one days. New Jerusalem Bible, Moffatt, and New American Bible express this clearly by translating “three full weeks.” An American Translation and Revised English Bible have the same idea, with “three whole weeks.”

Quoted with permission from Péter-Contesse, René & Ellington, John. A Handbook on Daniel. (UBS Helps for Translators). New York: UBS, 1994. For this and other handbooks for translators see here .