कठोपनिषत् (1.20)
येयं प्रेते विचिकित्सा मनुष्ये- ऽस्तीत्येके नायमस्तीति चैके । एतद्विद्यामनुशिष्टस्त्वयाऽहं … ॥ २०॥
Translation (Prabhavananda and Manchester)
(Nachiketa to Yama)
"When a man dies, there is this doubt: Some say, he is; others say, he is not. Taught by you, I would know the truth…"