Charak Samhita
वाते स्वाद्वम्लसान्द्रत्वात् सद्यस्कमविदाहि तत्। तस्मात् तक्रप्रयोगा ये जठराणां तथाऽर्शसाम्॥११९॥
Freshly churned butter milk does not cause burning sensation; therefore, buttermilk is very useful in treatment of udara, arśa and all grahanidosha
english translation
vAte svAdvamlasAndratvAt sadyaskamavidAhi tat। tasmAt takraprayogA ye jaTharANAM tathA'rzasAm॥119॥
hk transliteration by Sanscript