The Tibetan Book of the Dead
Book II: Method of Preventing Entry into a Womb
The instructions for preventing the being from entering are thus: O nobly-born, (so-and-so by name,) whosoever may have been thy tutelary deity, tranquilly meditate upon him-as upon the reflection of the moon in water, apparent yet non-existent [as a moon], like a magically-produced illusion. If thou hast no special tutelary, meditate either upon the Compassionate Lord or upon me; and, with this in mind, meditate tranquilly.