The Compendium of Kāśyapa 8.8.81

8.8.81

bhuktavantaṃ ca tailasya prasṛtenānuvāsayet
vāyuḥ praśāmyate tena nirūheṇa pracālitaḥ

And when he has eaten, one should administer an unctuous enema with a handful of oil; / by that means the vāta displaced by the non-unctuous enema is pacified.