Srimad Bhagavatam Canto 05, Chapter 04, Text 01

SB 5.4.1

sri-suka uvaca
atha ha tam utpattyaivabhivyajyamana-bhagaval-laksanam samyopasama-vairagyaisvarya-maha-vibhutibhir anudinam edhamananubhavam prakrtayah praja brahmana devatas cavani-tala-samavanayatitaram jagrdhuh.
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
Sri Sukadeva Gosvami said: As soon as the Lord was born as the son of Maharaja Nabhi, He manifested symptoms of the Supreme Lord, such as marks on the bottoms of His feet [the flag, thunderbolt, etc.]. This son was equal to everyone and very peaceful. He could control His senses and His mind, and, possessing all opulence, He did not hanker for material enjoyment. Endowed with all these attributes, the son of Maharaja Nabhi became more powerful day after day. Due to this, the citizens, learned brahmanas, demigods and ministers wanted Rsabhadeva to be appointed ruler of the earth.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
In these days of cheap incarnations, it is very interesting to note the bodily symptoms found in an incarnation. From the very beginning of His birth, it was observed that Rsabhadeva’s feet were marked with the transcendental signs (a flag, thunderbolt, lotus flower, etc.). In addition to this, as the Lord began to grow He became very prominent. He was equal to everyone. He did not favor one person and neglect another. An incarnation of God must have the six opulences — wealth, strength, knowledge, beauty, fame and renunciation. It is said that although Rsabhadeva was endowed with all opulences, He was not at all attached to material enjoyment. He was self-controlled and therefore liked by everyone. Due to His superexcellent qualities, everyone wanted Him to rule the earth. An incarnation of God has to be accepted by experienced people and by the symptoms described in the sastras. An incarnation is not accepted simply by the adulation of foolish people.
Srimad Bhagavatam Canto 05, Chapter 04, Text 02