Vaisesika Sūtra 1.1.17

एकद्रव्यमगुणं संयोगविभागेष्वानपेक्षकारणमिति कर्मलक्षणम् ॥१७॥

A single substance is without qualities, and is independent of the cause, by its combination and disjunction. This is the characteristics of movement (karma).