瑜伽師地論略纂 8.159

8.159

論得神足名因緣中云「彼能到此，故名神足」者，即能往能還等，名神足，定界果也。欲等為因，能得此定神，故名神足。

In the causes and conditions for obtaining the name 'basis of psychic power', where the treatise says, "that can reach this, hence it is called a basis of psychic power": that is, being able to go, being able to return, and so forth is called a basis of psychic power, which is the fruit of the realm of absorption. With desire and so forth as causes, one can obtain this absorption-psychic-power, hence it is called a basis of psychic power.