Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 23

Sanskrit:

परकायं विशन् सिद्ध आत्मानं तत्र भावयेत् ।पिण्डं हित्वा विशेत् प्राणो वायुभूत: षडङ्‍‍घ्रिवत् ॥ २३ ॥

ITRANS:

para-kāyaṁ viśan siddhaātmānaṁ tatra bhāvayetpiṇḍaṁ hitvā viśet prāṇovāyu-bhūtaḥ ṣaḍaṅghri-vat

Translation:

When a perfect yogī desires to enter another’s body, he should meditate upon himself within the other body, and then, giving up his own gross body, he should enter the other’s body through the pathways of air, as easily as a bee leaves one flower and flies into another.

Purport:

As air is inhaled into the body through the nostrils and mouth, similarly, the life air of the yogī’s subtle body travels through the pathways of external air and easily enters into the body of another person, just as the bee easily flies from flower to flower. One may admire a heroic man or beautiful woman and desire to experience life within their extraordinary material body. Such opportunities are available through the mystic perfection called para-kāya-praveśanam. Pure devotees, being absorbed in meditation upon the spiritual form of the Supreme Personality of Godhead, are not actually attracted to any material body. Thus the devotees remain transcendental and satisfied on the platform of eternal life.