Charak Samhita
एषां चाशु जरां स्नेहो यात्यम्बु सिकतास्विव। अतोऽन्येषां त्र्यहात्प्रायः स्नेहं पचति पावकः॥४७॥
As the water falling on sand gets absorbed immediately, similarly the fat given to these patients gets immediately digested. In case of others the agni generally digests sneha in three days.
english translation
eSAM cAzu jarAM sneho yAtyambu sikatAsviva। ato'nyeSAM tryahAtprAyaH snehaM pacati pAvakaH॥47॥
hk transliteration by Sanscript