Srimad Bhagavatam Canto 11, Chapter 11, Text 11

SB 11.11.11

evam viraktah sayana
na tatha badhyate vidvan
 tatra tatradayan gunan
An enlightened person fixed in detachment engages his body in lying down, sitting, walking, bathing, seeing, touching, smelling, eating, hearing and so on, but is never entangled by such activities. Indeed, remaining as a witness to all bodily functions, he merely engages his bodily senses with their objects and does not become entangled like an unintelligent person.
In the previous chapter, Uddhava asked Lord Krsna why an enlightened person, just like a conditioned soul, engages in external bodily functions. Here is the Lord’s answer. While engaged in bodily functions, an unintelligent person is attached to both the means and end of material life and therefore experiences intense lamentation and jubilation on the material platform. A self-realized soul, however, studies the inevitable defeat and suffering of ordinary persons and does not make the mistake of trying to enjoy the bodily functions even slightly. He instead remains a detached witness, merely engaging his senses in the normal functions of bodily maintenance. As indicated here by the word adayan, he engages something other than his actual self in material experience.
Srimad Bhagavatam Canto 11, Chapter 11, Text 10
Srimad Bhagavatam Canto 11, Chapter 11, Text 12-13