Tafsir of Al-Bayyinah 98:2

(A messenger) is an appositive to it [the clear evidence], an appositive of "the whole for the whole," or the predicate of an omitted subject—that is: "It is a messenger." Its tanwin (nunation) is for magnification, and what is intended by it is our Prophet, may Allah exalt him and grant him peace. His saying, the Glorified, "from Allah" is in the position of a description for him, yielding an attributional magnificence; thus, it confirms the intrinsic magnificence that the tanwin had already conveyed. His saying, the Exalted, "reciting purified scriptures" is a description of him, or a circumstantial qualifier (hal) from the pronoun in his first description, just as His saying, the Glorified...