This is derived from Shinran's saying 'Shinran does not seek further unique teachings; Shinran solely believes in, and propagates to others, the teachings of Nyorai.'
親鸞の言葉「更に親鸞珍らしき法をも弘めず、如来の教法を、われも信じ人にも教え聞かしむるばかりなり」から借りている。