Devibhagavatapurana 4.2.4

4.2.4

karmaṇaiva samutpattiḥ sarveṣāṃ nātra saṃśayaḥ |
anādinidhanā jīvāḥ karmabījasamudbhavāḥ ||

It was the seed of Karma whence the Jîvas (the individual embodied souls) arose with neither any beginning nor any end. Those Jîvas go often and often incarnating in numberless varieties of wombs and then go to dissolution. When this Karma ceases, the Jîvas then are never to have any more connection with any other body.