佛說觀佛三昧海經 3.7

3.7

「云何觀如來師子欠相？佛張口時，如師子王口方正等，口兩吻邊流出三光，其光金色過踰前光百千萬倍，上入耳光圍遶諸髮，從枕骨出遶前圓光，一一畫間有三化佛；一一化佛有二梵王以為侍者，是名如來師子欠相。

“How does one contemplate the mark of the Tathāgata’s lion yawn? When the Buddha opens his mouth, it is square and even like that of a lion king. From both corners of the mouth flow forth three rays of light; their golden color exceeds the previous light by hundreds of thousands of ten millions of times, ascending into the light of the ears, circling the hair, and emerging from the occipital bone to circle the preceding halo. Between each line there are three transformation Buddhas; each transformation Buddha has two Brahmā kings as attendants. This is called the mark of the Tathāgata’s lion yawn.”