Kol Nashim: Rosh Hodesh Shevat

by Rabbi Elizabeth Goldstein on Sefaria

שמות י״ב:א׳-ב׳
(א) וַיֹּ֤אמֶר יי אֶל־מֹשֶׁ֣ה וְאֶֽל־אַהֲרֹ֔ן בְּאֶ֥רֶץ מִצְרַ֖יִם לֵאמֹֽר׃ (ב) הַחֹ֧דֶשׁ הַזֶּ֛ה לָכֶ֖ם רֹ֣אשׁ חֳדָשִׁ֑ים רִאשׁ֥וֹן הוּא֙ לָכֶ֔ם לְחָדְשֵׁ֖י הַשָּׁנָֽה׃

Exodus 12:1-2(1) And the LORD spoke unto Moses and Aaron in the land of Egypt, saying: (2) ’This month shall be unto you the beginning of months; it shall be the first month of the year to you.

Talmud Yerushalmi Ta'anit 1:6
Women who refrain from work on Rosh Chodesh [= the first day of a lunar month] are following an established custom. [Read Complete Source Sheet]