Srimad-Bhagavatam: Canto 9 - Chapter 1 - Verse 11
कस्यचित् त्वथ कालस्य नासत्यावाश्रमागतौ ।तौ पूजयित्वा प्रोवाच वयो मे दत्तमीश्वरौ ॥ ११ ॥
kasyacit tv atha kālasyanāsatyāv āśramāgatautau pūjayitvā provācavayo me dattam īśvarau
Thereafter, some time having passed, the Aśvinī-kumāra brothers, the heavenly physicians, happened to come to Cyavana Muni’s āśrama. After offering them respectful obeisances, Cyavana Muni requested them to give him youthful life, for they were able to do so.
The heavenly physicians like the Aśvinī-kumāras could give youthful life even to one who was advanced in age. Indeed, great yogīs, with their mystic powers, can even bring a dead body back to life if the structure of the body is in order. We have already discussed this in connection with Bali Mahārāja’s soldiers and their treatment by Śukrācārya. Modern medical science has not yet discovered how to bring a dead body back to life or bring youthful energy to an old body, but from these verses we can understand that such treatment is possible if one is able to take knowledge from the Vedic information. The Aśvinī-kumāras were expert in Āyur-veda, as was Dhanvantari. In every department of material science, there is a perfection to be achieved, and to achieve it one must consult the Vedic literature. The highest perfection is to become a devotee of the Lord. To attain this perfection, one must consult Śrīmad-Bhāgavatam, which is understood to be the ripe fruit of the Vedic desire tree (nigama-kalpa-taror galitaṁ phalam).