Point Four, on the passage “At that time the bodhisattvas, respectfully complying with the Buddha’s will and at the same time wishing to fulfill their own original vows, proceeded in the presence of the Buddha to roar the lion’s roar and to make a vow.”
The Record of the Orally Transmitted Teachings says: To comply with the Lotus Sutra is what is meant by “respectfully complying with the Buddha’s will.” By the Buddha’s will is meant Nam-myoho-renge-kyo.
Now when Nichiren and his followers chant Nam-myoho-renge-kyo, it means that they are “respectfully complying with the Buddha’s will.”
---> http://www.nichirenlibrary.org/en/ott/PART-1/13