PB, 6, 5, 21.0 yannvityāhur antarāśvaḥ prāsevau yujyate 'ntarā śamye anaḍvān ka udgātṝṇāṃ yoga iti yad droṇakalaśam upasīdanti sa eṣāṃ yogas tasmād yuktair evopasadyaṃ na hy ayukto vahati //