法華義疏 8.255

8.255

Some say: the Buddha's countenance has relaxation and tension, and thus one knows whether he accepts or does not accept. Some say: the upward or downward movement of the bodily light indicates it, and thus there is acceptance or non-acceptance. Some say: when he first attained the Way, if the Buddha had someone announce his title and was silent, that was accepting the request; at the time of nirvāṇa, being silent was not accepting the request.