いまの見佛聞法は、佛祖面面の行持よりきたれる慈恩なり。佛祖もし單傳せずは、いかにしてか今日にいたらん。一句の恩なほ報謝すべし、一法の恩なほ報謝すべし。いはんや正法眼藏無上大法の大恩、これを報謝せざらんや。一日に無量恆河沙の身命すてんこと、ねがふべし。法のためにすてんかばねは、世世のわれら、かへりて禮拜供養すべし。諸天龍神ともに恭敬尊重し、守護讃歎するところなり、道理それ必然なるがゆゑに。
 西天竺國には、髑髏をうり髑髏をかふ婆羅門の法、ひさしく風聞せり。これ聞法の人の髑髏形骸の功徳おほきことを尊重するなり。いま道のために身命をすてざれば、聞法の功徳いたらず。身命をかへりみず聞法するがごときは、その聞法成熟するなり。この髑髏は、尊重すべきなり。いまわれら、道のためにすてざらん髑髏は、他日にさらされて野外にすてらるとも、たれかこれを禮拜せん、たれかこれを賣買せん。今日の精魂、かへりてうらむべし。鬼の先骨をうつありき、天の先骨を禮せしあり。いたづらに塵土に化するときをおもひやれば、いまの愛惜なし、のちのあはれみあり。もよほさるるところは、みん人のなみだのごとくなるべし。いたづらに塵土に化して人にいとはれん髑髏をもて、よくさいはひに佛正法を行持すべし。
 このゆゑに、寒苦をおづることなかれ、寒苦いまだ人をやぶらず、寒苦いまだ道をやぶらず。ただ不修をおづべし、不修それ人をやぶり、道をやぶる。暑熱をおづることなかれ、暑熱いまだ人をやぶらず、暑熱いまだ道をやぶらず。不修よく人をやぶり、道をやぶる。麥をうけ、蕨をとるは、道俗の勝躅なり。血をもとめ、乳をもとめて、鬼畜にならはざるべし。ただまさに行持なる一日は、緒佛の行履なり。(http://www.shomonji.or.jp/soroku/genzou16b/index.html)

In that we have encountered Buddha and heard the Dharma today, we are indebted for the loving-kindness evinced by the ceaseless practice of each and every Buddha and Ancestor. Had the Buddhas and Ancestors not directly Transmitted the Dharma to us, how could It possibly have reached us in the present? We should repay our indebtedness for even a single line of verse, and we should repay our indebtedness for even a single Teaching. How much more should we repay our immeasurable indebtedness for the unsurpassed great Dharma of the Treasure House of the Eye of the True Teaching! All day long, we should desire to give up our own lives, which have been as innumerable as the sands of the Ganges. In generation after generation, we should bow in deepest respect and make alms offerings to the bodies that we have abandoned for the sake of the Dharma. Together with all the celestial beings, dragons, and divine spirits, we should venerate and esteem these bodies, for they are something to protect and praise, because the principle of gratitude underlying this veneration is indispensable.
The practice of the Brahmans who buy and sell skulls has long been reported in India. They have deeply revered the numerous, meritorious virtues of the skulls and bones of those who have hearkened to the Dharma. Now, if we do not give up our own lives for the sake of the Way, we will not attain the meritorious virtue of having heard the Teaching. If we hearken to the Dharma without giving a thought for life and limb, that hearing of the Dharma will fully ripen, and this skull of ours will be revered. The skull that we have not yet given up for the sake of the Way will one day be tossed in some vacant field and left to bleach in the sun. Who then will bow out of respect for it? Who would buy or sell it as a relic? We surely would look back upon our attitude and spirit of today with regret.
There was once a demon who angrily reduced his former bones to dust, and there was a celestial being who bowed in respect to his former bones. When we think ahead to a time when, no matter what, we will be transformed into dust, those of us who had no attachments to craving in our present life will feel sympathy for others in the future. And this feeling of sympathy that is aroused may well be akin to the tears of an onlooker. Fortunately, by using our present skull—which will ultimately turn to dust and which people may well look upon with disgust—we can ceaselessly practice the True Teaching of the Buddha. For this reason, do not fear suffering from the cold, for suffering from the cold has yet to destroy anyone, nor has it ever destroyed the Way. Do not fear training, for not training is what destroys a person and what destroys the Way. Do not fear the heat of summer, for the heat of summer has yet to destroy anyone, nor has it ever destroyed the Way. Not training can well destroy both a person and the Way. The accepting of barley and the choosing of bracken, which involved both monks and laity, are excellent examples of this. We should not copy hellish creatures and beasts by seeking for blood or seeking for milk. Simply, ceaseless practice all day long is precisely what the everyday practice of Buddhas is.
(https://www.shastaabbey.org/pdf/shoboAll.pdf)