Srimad Bhagavatam Canto 03, Chapter 21, Text 08

SB 3.21.8

tavat prasanno bhagavan
 puskaraksah krte yuge
darsayam asa tam ksattah
 sabdam brahma dadhad vapuh
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Then, in the Satya-yuga, the lotus-eyed Supreme Personality of Godhead, being pleased, showed Himself to that Kardama Muni and displayed His transcendental form, which can be understood only through the Vedas.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Here two points are very significant. The first is that Kardama Muni attained success by yoga practice in the beginning of Satya-yuga, when people used to live for one hundred thousand years. Kardama Muni attained success, and the Lord, being pleased with him, showed him His form, which is not imaginary. Sometimes the impersonalists recommend that one can arbitrarily concentrate one’s mind on some form he imagines or which pleases him. But here it is very clearly said that the form which the Lord showed to Kardama Muni by His divine grace is described in the Vedic literature. Sabdam brahma: the forms of the Lord are clearly indicated in the Vedic literature. Kardama Muni did not discover any imaginary form of God, as alleged by rascals; he actually saw the eternal, blissful and transcendental form of the Lord.
Srimad Bhagavatam Canto 03, Chapter 21, Text 07
Srimad Bhagavatam Canto 03, Chapter 21, Text 09