The Compendium of Caraka 6.15.201

6.15.201

sandhukṣati tathā vahnireṣāṃ vidhivadindhanaiḥ/
snehameva paraṃ vidyāddurbalānaladīpanam//

Thus the fire of these patients blazes up duly by means of fuels. / One should know unctuous substance alone to be superior for stimulating a weak digestive fire;