अर्थ
Others, who are devoted to {the secret science of} breath-control, offer the incoming breath (Prāna Vāyu) into the outgoing breath (Apāna Vāyu) and the outgoing breath (Apāna Vāyu) into the incoming breath (Prāna Vāyu). They thus arrest inhalation and exhalation {to remain in Samādhi—the highest state of concentration in God or the inner Self—without any physical movement, including inhalation and exhalation} rendering breathing unnecessary through the practice of breath control (prānāyāma). By regulating their diet, other devotees offer all kinds of prānas (breath and other airs within the body) as oblations in the fire of the {one common} Prāna. All these spiritual aspirants are knowers of yajnas (spiritual pursuits) and have their sins destroyed by yajna. (4:29-30)
टीका
These two verses contain the secret science of Kriyā Yoga, a form of the ancient science of meditation.
संस्कृत श्लोक
अपाने जुह्वति प्राणं प्राणेऽपानं तथापरे ।
प्राणापानगती रुद्ध्वा प्राणायामपरायणाः ॥ ४:२९ ॥
पदच्छेद
अपाने जुह्वति प्राणम्, प्राणे अपानम् तथा अ-परे,
प्राण-अपान-गती रुद्ध्वा, प्राण-आयाम-परायणाः।
संस्कृत श्लोक
अपरे नियताहाराः प्राणान्प्राणेषु जुह्वति ।
सर्वेऽप्येते यज्ञविदो यज्ञक्षपितकल्मषाः ॥ ४:३० ॥
पदच्छेद
अपरे नियत-आहाराः प्राणान् प्राणेषु जुह्वति,
सर्वे अपि एते यज्ञ-विदः, यज्ञ-क्षपित कल्मषाः।