Is what is stated in Musnad Ahmad true, that 200 verses from Surat Al-Ahzab have been abrogated, and does this include the verse of stoning: "The married man and the married woman, if they commit adultery, stone them without doubt, as a deterrent from Allah, and Allah is Mighty and Wise"?

First: Surah (definition) Al-Ahzab was as great as Surah Al-Baqarah, but most of it was abrogated. This abrogation was either an abrogation of recitation without the ruling, such as the verse of stoning (Ayat Al-Rajm), or an abrogation of both recitation and ruling.

Second: Regarding what was narrated from Ibn Mas'ud - may Allah be pleased with him - concerning his denial that Al-Mu'awwidhatayn (Surahs Al-Falaq and An-Nas) are part of the Qur'an, scholars have several opinions: 1. This statement is not authentically attributed to him; rather, it is a fabricated lie. 2. He only denied their inclusion in the Mushaf (definition) (written copy of the Qur'an), not their being part of the Qur'an itself. 3. He initially denied their Qur'anic nature, but when it became clear to him that they were indeed part of the Qur'an, he included them in his Mushaf and recanted his earlier statement.