The ruling on sending blessings upon the Prophet (peace and blessings be upon him) with the heart only, without uttering them or moving the tongue

Question:
In her other question, she says: Sometimes I read from a book silently, just looking at it without moving my tongue. If there is a phrase saying “may Allah send blessings and peace upon him,” am I required to utter it in order to have sent blessings upon the Messenger of Allah (peace and blessings be upon him)? Or do I read it as I read the rest of the text, just by looking at it?

Answer:
It is necessary to utter the blessings and peace upon the Prophet (peace and blessings be upon him); because that is a verbal act of worship, so it is necessary to utter it. Yes.