Which Surah was not mentioned in the Mushaf?

The Quran, which is worshipped through its recitation, is what is contained between the two covers of the Mushaf (definition), from Al-Fatihah to An-Nas. Anything outside of that is not Quran, such as what had its recitation and ruling abrogated, even if it was sometimes called a Surah (definition), as in the statement of Abu Musa Al-Ash'ari about a Surah that was "raised." Such texts are not considered true Surahs because they are not Quran, and Allah has undertaken to preserve the Quran from any addition or alteration.