140
Śrīmad-Bhāgavatam
[Canto 10, Ch. 8]
the most famous Nanda Mahārāja, and his wife, Dharā, appeared as mother Yaśodā.
PURPORT
Because whenever Krṣṇa appears on this earth He superficially needs a father and mother, Droṇa and Dharā, His eternal father and mother, appeared on earth before Krṣṇa as Nanda Mahārāja and Yaśodā. In contrast to Sutapā and Prśnigarbha, they did not undergo severe penances and austerities to become the father and mother of Krṣṇa. This is the difference between  nitya-siddha  and  sādhana-siddha .
TEXT 51
ततो भक्तिर्भगवति पुत्रीभूते जनार्दने । दम्पत्योर्नितरामासीद् गोपगोपीषु भारत ॥५१॥
tato bhaktir bhagavati putrī-bhūte janārdane dampatyor nitarām āsīd gopa-gopīṣu bhārata
tataḥ —thereafter;  bhaktiḥ bhagavati —the cult of  bhakti , devotional service unto the Supreme Personality of Godhead;  putrī-bhūte —in the Lord, who had appeared as the son of mother Yaśodā;  janārdane —in Lord Krṣṇa;  dam-patyoḥ —of both husband and wife;  nitarām —continuously;  āsīt —there was;  gopa-gopīṣu —all the inhabitants of Vṛndāvana, the  gopas  and the  gopīs , associating with Nanda Mahārāja and Yaśodā and following in their footsteps;  bhārata —O Mahārāja Parikṣit.
TRANSLATION
Thereafter, O Mahārāja Parikṣit, best of the Bhāratas, when the Supreme Personality of Godhead became the son of Nanda Mahārāja and Yaśodā, they maintained continuous, unswerving devotional love in parental affection. And in their association, all the other inhabitants of Vṛndāvana, the  gopas  and  gopīs , developed the culture of  krṣṇa-bhakti .