Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 2
य: पञ्चहायनो मात्रा प्रातराशाय याचित: ।तन्नैच्छद्रचयन् यस्य सपर्यां बाललीलया ॥ २ ॥
yaḥ pañca-hāyano mātrāprātar-āśāya yācitaḥtan naicchad racayan yasyasaparyāṁ bāla-līlayā
He was one who even in his childhood, at the age of five years, was so absorbed in the service of Lord Kṛṣṇa that when he was called by his mother for morning breakfast, he did not wish to have it.
From his very birth, Uddhava was a natural devotee of Lord Kṛṣṇa, or a nitya-siddha, a liberated soul. From natural instinct he used to serve Lord Kṛṣṇa, even in his childhood. He used to play with dolls in the form of Kṛṣṇa. He would serve the dolls by dressing, feeding and worshiping them, and thus he was constantly absorbed in the play of transcendental realization. These are the signs of an eternally liberated soul. An eternally liberated soul is a devotee of the Lord who never forgets Him. Human life is meant for reviving one’s eternal relation with the Lord, and all religious injunctions are meant for awakening this dormant instinct of the living entity. The sooner this awakening is brought about, the quicker the mission of human life is fulfilled. In a good family of devotees, the child gets the opportunity to serve the Lord in many ways. A soul who is already advanced in devotional service has the opportunity to take birth in such an enlightened family. This is confirmed in the Bhagavad-gītā (6.41). Śucīnāṁ śrīmatāṁ gehe yoga-bhraṣṭo ’bhijāyate: even the fallen devotee gets the opportunity to take his birth in the family of a well-situated brāhmaṇa or in a rich, well-to-do mercantile family. In both these families there is a good opportunity to revive one’s sense of God consciousness automatically because particularly in these families the worship of Lord Kṛṣṇa is regularly performed and the child gets the opportunity to imitate the process of worship called arcanā. The pāñcarātrikī formula for training persons in devotional service is temple worship, whereby the neophytes get the opportunity to learn devotional service to the Lord. Mahārāja Parīkṣit also used to play with Kṛṣṇa dolls in his childhood. In India the children in good families are still given dolls of the Lord like Rāma and Kṛṣṇa, or sometimes the demigods, so that they may develop the aptitude of service to the Lord. By the grace of the Lord we were given the same opportunity by our parents, and the beginning of our life was based on this principle.