She fasted all the days of her widowhood: She fasted means that she went without food for a specified period of time (see 4.13). “During that entire period” (Good News Translation) avoids the repetition in all the days of her widowhood. “Except when fasting was forbidden” (Good News Translation) is a helpful addition to explain what the ancient Jewish reader would already know: the special observances named in the rest of the verse were days when Jewish practice forbade fasting.

The sabbath was the Israelite “day of rest,” and this will be a good way to translate it in many languages.

The day of the new moon marked the first day of the month in the Jewish calendar. Observance of this day was much like Sabbath observance (Num 28.9-15). Sabbath restrictions on work applied (Amos 8.5), and like the Sabbath, it was a day of rejoicing (Hos 2.11). Both Good News Translation and Contemporary English Version refer to it as the “New Moon Festival.”

The feasts and days of rejoicing of the house of Israel: The feasts and days of rejoicing (Good News Translation “festivals and holidays”; Contemporary English Version “every joyous festival”) would include the Passover, the Feast of Unleavened Bread, the Feast of Weeks, and the Festival of Booths/Shelters. House of Israel is an idiom referring to the Israelite nation (see 4.15). Of the house of Israel may be rendered “which the people of Israel observed [or, celebrated].”

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on Judith. (UBS Helps for Translators). New York: UBS, 2001. For this and other handbooks for translators see here.