Charak Samhita
बस्तिनेत्रसमद्रव्यं धूमनेत्रं प्रशस्यते। दूराद्विनिर्गतः पर्वच्छिन्नो नाडीतनूकृतः ॥५१॥
The smoking pipe recommended the most is a straight one having three knots/bulges, having the proximal caliber of the size of a ziziphus-stone and is made of the same materials as those of the basti nozzle.
english translation
bastinetrasamadravyaM dhUmanetraM prazasyate। dUrAdvinirgataH parvacchinno nADItanUkRtaH ॥51॥
hk transliteration by Sanscript