Patanjali Yoga Sutra – III – 39

Going places

Bandhakarana Shaithilyath prachara samvedanaccha chittasya parashareeraveshaha||

When the cause for bondage i.e. ignorance or the non-apprehension of reality is gone, then by the proper knowledge of entry and exit, the yogi is able to enter into different bodies. This achievement called Parakaya Pravesha was possible by many Siddhas. – SS