1 Preface يسYusuf AliYa Sin.1Some Commentators take Ya to be the vocative article, and Sin to be the abbreviation of Insan, Sin being the only “Firm Letter” in the word. In that case it would be an address to man. “O man!” But “man” in this connection is understood to mean the Leader of man, the noblest of mankind, Muḥammad, the Prophet of God. For this Sūra deals mainly with the Prophet and his Message. But no dogmatic assertion can be made about the Abbreviated Letters, for which see Appendix 1, following S. 2. Ya Sin is usually treated as a title of the Prophet.