Bhagavatapurana 6.8.5

6.8.5

nārāyaṇaparaṃ varma sannahyedbhaya āgate /
pādayorjānunorūrvorudare hṛdy athorasi //

5. When a danger befalls him he should put on the coat-of mail (the means of protection) constituted of Narayana’s essence; [Through the agency of the gods, the Bhutas, and one’s own sinful actions, the person becoming imbued with the spirit of Narayana] he should place (_i.e._, contemplate the Lord) in the feet, in the knee-joints, the thighs, the belly, the heart and the chest;