Yoga Sūtra Chapter Four verse 10

तासामनादित्वं चाशिषो नित्यत्वात् ॥१०॥

tāsām-anāditvaṃ cā-āśisaḥ nityatvāt ||10||

And the beginninglessness of these is due to the eternality of primordial desire.

tāsām - of theseanāditva - beginninglessnessca - andāśis - premordial desirenityatvā - eternality