‘The one-mind which manifests either as thought (unen) or no-thought (munen) must be something which is beyond these conditions. It must be the light which illuminates everywhere and is never clouded. As soon as you become clearly aware of this light, you will be released from the limitation of delusory thoughts, and the buddha’s wisdom will be realized. This is called the wondrous mind of nirvana. This is nothing other than Self-Enjoyment Samadhi. Shakyamuni’s six years of sitting, Bodhidharma’s nine years of facing the wall, Chan Master Tiantong Rujing’s “just sitting” (shikantaza) are all examples of the practice-enlightenment of this samadhi.’ (Jijuyu Zammai)
Another text from my archive, which also illuminates Dogen’s line.