dvah-sthesu pauresv api sayitesv atha
dvaras ca sarvah pihita duratyaya
tah krsna-vahe vasudeva agate
svayam vyavaryanta yatha tamo raveh
vavarsa parjanya upamsu-garjitah
seso ’nvagad vari nivarayan phanaih
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
By the influence of Yoga-maya, all the doorkeepers fell fast asleep, their senses unable to work, and the other inhabitants of the house also fell deeply asleep. When the sun rises, the darkness automatically disappears; similarly, when Vasudeva appeared, the closed doors, which were strongly pinned with iron and locked with iron chains, opened automatically. Since the clouds in the sky were mildly thundering and showering, Ananta-naga, an expansion of the Supreme Personality of Godhead, followed Vasudeva, beginning from the door, with hoods expanded to protect Vasudeva and the transcendental child.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Sesa-naga is an expansion of the Supreme Personality of Godhead whose business is to serve the Lord with all necessary paraphernalia. When Vasudeva was carrying the child, Sesa-naga came to serve the Lord and protect Him from the mild showers of rain.