Siman 283
Presented here for study, not as a practical ruling. The Shulchan Aruch rules by Sephardi custom, the Rema's glosses by Ashkenazi custom, and the Kitzur follows Ashkenazi custom. For a practical question, ask your rabbi.
א מַה שֶּׁאֵין מוֹצִיאִין בְּשַׁבָּת סֵפֶר שֵׁנִי לִקְרוֹת פָּרָשַׁת הַמּוּסָפִים, מִפְּנֵי שֶׁאֵין בָּהּ אֶלָּא שְׁנֵי פְּסוּקִים.
1 We do not take a second Torah out on Shabbat to read the maftir because it only has two pesukim [note: this means that the passage describing the Mussaf offering of Shabbos contains only two verses, and no fewer than three verses may be read from a Torah scroll]