Vaisesika Sūtra 3.1.12

भूतं भूतस्य ॥१२॥

bhūtaṁ bhūtasya ॥12॥

[भूतम् (bhūtam) - that which has come into being; भूतस्य (bhūtasya) - of that which previously existed.]

That which has come into being from that which previously existed.