Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 14

Sanskrit:

प्रागयं वसुदेवस्य क्‍वचिज्जातस्तवात्मज: ।वासुदेव इति श्रीमानभिज्ञा: सम्प्रचक्षते ॥ १४ ॥

ITRANS:

prāg ayaṁ vasudevasyakvacij jātas tavātmajaḥvāsudeva iti śrīmānabhijñāḥ sampracakṣate

Translation:

For many reasons, this beautiful son of yours sometimes appeared previously as the son of Vasudeva. Therefore, those who are learned sometimes call this child Vāsudeva.

Purport:

Garga Muni indirectly disclosed, “This child was originally born as the son of Vasudeva, although He is acting as your child. Generally He is your child, but sometimes He is the son of Vasudeva.”