Bhagavatapurana 10.2.5

10.2.5

saptamo vaiṣṇavaṃ dhāma yam anantaṃ pracakṣate /
garbho babhūva devakyā harṣa-śoka-vivardhanaḥ //

4. Some, his relations, submitted to him and continued to serve him (viz., Akrura and others who were residents of Mathura) when Kamsa, the son of Ugrasena, had killed six children of Devaki, 5. The seventh was a ray of Vishnu known as Ananta and this conception was a source of both joy and grief to Devaki.