Jñāneśvarī (commentary on the Bhagavadgītā) 4.147

4.147

apare niyatāhārāḥ prāṇān prāṇeṣu juhvati
sarve 'py ete yajñavido yajñakṣapitakalmaṣāḥ
eka vajrayogakrameṃ |
sarvāhārasaṃyameṃ |
prāṇīṃ prāṇu saṃbhrameṃ |
havana karitī ||

Some, following the practice of vajrayoga,
through the restraint of all food,
offer prāṇa into prāṇa
with zealous resolve.