The Compendium of Caraka 1.5.109

1.5.109

yadarthaṃ yāni cāsyena dhāryāṇi kavalagrahe/
tailasya ye guṇā &diṣṭāḥ śirastailaguṇāśca ye//

for what purpose and which [liquids] are to be held in the mouth in gargling;
the qualities that are taught of oil, and the qualities of head oil;