Those who have full knowledge of self-realization, who know very well that the spirit soul is eternal whereas the body is perishable, are not overwhelmed by lamentation. But persons who lack knowledge of self-realization certainly lament. Therefore it is difficult to educate a person in illusion.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
अथ नित्यमनित्यं वा नेह शोचन्ति तद्विदः । नान्यथा शक्यते कर्तुं स्वभावः शोचतामिति
atha nityamanityaṃ vā neha śocanti tadvidaḥ | nānyathā śakyate kartuṃ svabhāvaḥ śocatāmiti
SB 7.2.49