Bhagavad Gita Bhasya (Gambhirananada)

forces, withdrawal of the organs, etc., is a sacrifice;
and svadhyaya-jnana-yajnah, performers of
sacrifices through study and knowledge.
Sacrificers through study are those to whom the
study of Rg-veda etc. accroding to rules is a
sacrifice. And sacrificers through knowledge are
those to whom proper understanding of the
meaing of the scriptures is a sacrifice. Others are
yatayah, ascetics, who are deligent; samsita-vratah,
in following severe vows. Those whose vows
(vratah) have been fully sharpened (samsita), made
very rigid, are samsita-vratah. [Six kinds of
sacrifices have been enumerated in this verse.]
Further,
4.29 Constantly practising control of the vital forces
by stopping the movements of the outgoing and
the incoming breaths, some offer as a sacrifice the
outgoing breath in the incoming breath; while still
others, the incoming breath in the outgoing breath.
English Translation of Sri Sankaracharya's Sanskrit
Commentary - Swami Gambhirananda
4.29 Pranayama-parayanah, constantly practising
control of the vital forces-i.e. they practise a form of
pranayama called Kumbhaka (stopping the breath
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