Q: What is the mas-alah pertaining to skipping a Surah and reciting another Surah in the second Rakaat? A person read Surah Itha Jaa’a Nasrullahi … in the first Rakaat and Surah Qul Huwallaahu Ahad in the second Rakaat. Is this in order?
A. It is best to recite the next Surah in the second Rakaat, Surah Tabbat Yadaa in the question. Omitting two or more Surahs in between is also perfectly permissible. In the case of omitting just one Surah, if the Surah omitted is much lengthier than the previous Surah then omitting this longer Surah will also be permissible without any karaahat (reprehensibility.
The instance of karaahat is when the Surah omitted is shorter or equal or only slightly longer than the previous Surah. In these cases it will be Makrooh-e-Tanzeehi to omit that Surah. This mas-alah applies to Fardh Salaats, not to Nafl Salaats.