佛說觀佛三昧海經 9.37

9.37

"For those who delight in reverse contemplation: they should look upward and contemplate sequentially starting from the toes of the image. First, contemplate the toes, focusing the mind exclusively. Fixing upon the Buddha's toes for seven days, whether closing the eyes or opening the eyes, cause the golden image's toes to be clearly seen. Gradually and sequentially, contemplate the insteps of both feet, causing them to be clearly seen. Next, contemplate the calves like those of the eneya antelope king. Once the mind is focused, proceed sequentially up to the uṣṇīṣa. If viewing the face from the uṣṇīṣa is not clear, repent once more and redouble your efforts in self-exertion. Due to the purity of the precepts, the face of the Buddha's image will be seen clearly and distinctly like a mirror of genuine gold. Having performed this contemplation, contemplate the ūrṇā-hair between the eyebrows, which is like a crystal bead coiling to the right. When this mark appears, see the Buddha's eyebrows and eyes as if painted by a divine painter. Having seen this, next contemplate the light of the crown, causing it to be distinct and clear. Such a sequence of marks is called reverse contemplation."