The material body is also my spiritual master because it teaches me detachment. Being subject to creation and destruction, it always comes to a painful end. Thus, although using my body to acquire knowledge, I always remember that it will ultimately be consumed by others, and remaining detached, I move about this world.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
देहो गुरुर्मम विरक्तिविवेकहेतुः बिभ्रत्स्म सत्त्वनिधनं सततार्त्युदर्कम् । तत्त्वान्यनेन विमृशामि यथा तथापि पारक्यमित्यवसितो विचराम्यसङ्गः
deho gururmama viraktivivekahetuḥ bibhratsma sattvanidhanaṃ satatārtyudarkam | tattvānyanena vimṛśāmi yathā tathāpi pārakyamityavasito vicarāmyasaṅgaḥ
SB 11.9.25