Necessary inference . We are not expressly told he ever went into the water. However, to come out of the water, he had to go into the water - hence the necessary inference. Not a few, even in the Lord's church, are now passed questioning the validity of necessary inference and approved example. Some of these objections are already progressing to the point of also questioning and even denying express command.
Authority is absolutely necessary .
Beloved, the scriptures are replete with one emphatic warning after another regarding the seriousness of being without authority. To be without law is to be without authority.