Is the saying mentioned in the dream, "O Allah, send prayers, peace, and blessings upon our master Muhammad and upon his family and companions, a pure and blessed prayer that You are pleased with, which You pray with me upon him," after visiting the Prophet's grave and repeating a specific supplication, from the work of Satan, or is it good that can be taught to people?

The first formula you were using to pray upon the Messenger of Allah, peace and blessings be upon him, is incorrect. This is because the phrase "as befits the majesty of Your Face and the greatness of Your power" is for the praise and glorification of Allah. As for the formula you heard the caller utter in your dream, there is no harm in it, and it is a righteous vision, for Satan does not command acts of obedience. The best formula for sending prayers and salutations upon the Messenger of Allah, peace and blessings be upon him, is the Salat al-Ibrahimiyyah.