SB 10.2.38

The soles of the Lord’s lotus feet are marked with śaṅkha-cakra-gadā-padma — conchshell, disc, club and lotus — and also by a flag and a thunderbolt. When Kṛṣṇa walks on this earth or in the heavenly planets, these marks are visible wherever He goes. Vṛndāvana-dhāma is a transcendental place because of Kṛṣṇa’s walking on this land frequently. The inhabitants of Vṛndāvana were fortunate to see these marks here and there. When Akrūra went to Vṛndāvana to take Kṛṣṇa and Balarāma away to the festival arranged by Kaṁsa, upon seeing the marks of the Lord’s lotus feet on the ground of Vṛndāvana, he fell down and began to groan. These marks are visible to devotees who receive the causeless mercy of the Supreme Personality of Godhead (tavānukampitām). The demigods were jubilant not only because the appearance of the Supreme Lord would do away with the burdensome demons, but also because they would be able to see upon the ground the transcendental marks from the soles of the Lord’s lotus feet. The gopīs always thought of the Lord’s lotus feet when He was walking in the pasturing grounds, and, as described in the previous verse, simply by thinking of the Lord’s lotus feet, the gopīs were fully absorbed in transcendence (āviṣṭa-cetā na bhavāya kalpate). Like the gopīs, one who is always absorbed in thought of the Lord is beyond the material platform and will not remain in this material world. It is our duty, therefore, always to hear, chant and think about the Lord’s lotus feet, as actually done by Vaiṣṇavas who have decided to live in Vṛndāvana always and think of the Lord’s lotus feet twenty-four hours a day.