What is the ruling if a minor who accepted Islam later claims not to have understood what they said?

Primary text

If a minor, whose comprehension of Islam was established by his actions being those of a rational person, subsequently claims he did not know what he said and retracts, his statement is not accepted, and his initial Islam is not invalidated. This is the established practice based on the view of Ahmad, because the comprehension of his rationality was established by his actions and utterances, similar to how the sanity of a sane person or the madness of an insane person is recognized. Any person who utters Islam and then denies knowing what they said is considered an apostate.