Vishnupurana 5.1.7

5.1.7

athāntarikṣe vāg uccaiḥ kaṃsam ābhāṣya sādaram
meghagambhīranirghoṣaṃ samābhāṣyedam abravīt //

Vasudeva formerly married the daughter of Devaka, the illustrious Devakí, a maiden of celestial beauty. After their nuptials, Kansa, the increaser of the race of Bhoja, drove their car as their charioteer. As they were going along, a voice in the sky, sounding aloud and deep as thunder, addressed Kansa, and said, "Fool that you are, the eighth child of the damsel whom you are driving in the car shall take away your life!" On hearing this, Kansa drew his sword, and was about to put Devakí to death; but Vasudeva interposed, saying, "Kill not Devakí, great warrior; spare her life, and I will deliver to you every child that she may bring forth." Appeased by which promise, and relying on the character of Vasudeva, Kansa desisted from the attempt.