It is based on a writing in "San Amidabutsu Ge" (Gatha in Praise of Amida Buddha), by Donran, that he saw Amida Nyorai and bowed from the bottom of his heart, showing his belief.
曇鸞が『讃阿弥陀佛偈』に、不可思議光一心帰命稽首礼と著し、自己の信念を表したことに基づく。