Matsyapurana 46.15

46.15

anujā tv abhavatkṛṣṇā subhadrā bhadrabhāṣiṇī
devakyāṃ tu mahātejā jajñe śūro mahāyaśāḥ //

(It is so stated in the Purâṇas, owing to the difference in Kalpa: otherwise it is laid down in the Bhâgavata that Kṛiṣṇa was born in the month of Bhâdra, on the 8th of the dark fortnight.) The sweet-speaking Subhadrâ, the beautiful sister of Kṛiṣṇa, was born after him. Both Kṛiṣṇa and Subhadrâ were born of Devakî.—15.