Is seeking permission obligatory when one is certain of consent?

This question is general. If the permission is for entering someone's home, then it is obligatory, for the Prophet, peace and blessings be upon him, said: "Indeed, permission was sought only on account of the gaze." If the permission is for disposing of something that belongs to another, then customary permission is equivalent to verbal permission. And permission is not obligatory if his رضا (contentment/consent) is known, and one disposes of it in a way that does not harm the owner.