Which is more correct to say: "Sayyiduna Muhammad, may Allah bless him and grant him peace" or "Muhammad, may Allah bless him and grant him peace," and is it a condition to use the word "Sayyiduna"?

If the phrase "Sayyiduna Muhammad" is used in the prayer (Salah), the call to prayer (Adhan), or in the prescribed remembrances (Adhkar) and supplications (Du'a) where the word "Sayyiduna" (our master) was not originally mentioned, then it is better to restrict oneself to what has been authentically reported in the Sunnah. However, in other contexts, there is no objection to saying "Sayyiduna Muhammad, peace and blessings be upon him," for he is our master and the master of all the Children of Adam. Allah has commanded us to venerate and revere him, and has forbidden us from raising our voices to him.