Shiva Purana

siva.sh/siva-purana/saturda-samhita/19/57

ब्रह्मप्रार्थनया विष्णुर्वसुदेवसुतोऽभवत् ।। धराभारावतारार्थं साधूनां रक्षणाय च ।। ५७।।

sanskrit

At the request of Brahmā, Viṣṇu was born as the son of Vasudeva in order to ease the burden of the Earth as well as to protect the good.

english translation

brahmaprArthanayA viSNurvasudevasuto'bhavat || dharAbhArAvatArArthaM sAdhUnAM rakSaNAya ca || 57||

hk transliteration by Sanscript