I think God is great enough to see into hearts and doesn’t need to hear a formula repeated out loud. But that’s me.
I John 1:9 “If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.”
Romans 10:10-13 “For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation. For the scripture saith, Whosoever believeth on him shall not be ashamed. For there is no difference between the Jew and the Greek: for the same Lord over all is rich unto all that call upon him. For whosoever shall call upon the name of the Lord shall be saved.”