The Shabbat immediately preceding Rosh Chodesh is called Shabbat Machar Chodesh (שבת מחר חודש) and the haftarah is 1 Shemuel 20:18-42. It is distinct from Shabbat Rosh Chodesh, Shabbat Mevarkhim, and Shabbat ha-Chodesh.
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