Even thought the Creator again raised doubts and questioned Buddhist teachings, there is even 'Treasury of the True Dharma Eye, The essence of the Buddha's enlightenment' and doubtful teachings that are not documented and go beyond orthodox teachings which are associated with the sage Mahakasyapa.
また大梵天王問仏決疑経にも「正法眼蔵・涅槃妙心、微妙（みみょう）法門あり、文字を立てず教外に別伝して迦葉に付属す」とある。