B.G 4.25 and 26
दैवमेवापरे यज्ञं योगिनः पर्युपासते। ब्रह्माग्नावपरे यज्ञं यज्ञेनैवोपजुह्वति ॥२५॥
श्रोत्रादीनींद्रियाण्यन्ये संयमाग्निषु जुह्वति। शब्दादीन् विषयानन्य इंद्रियाग्निषु जुह्वति ॥२६॥
Some engage in 'yajna' to worship the lord, while Yogis meditate on the absolute reality, the lord Brahman, as 'yajna'. Others make offerings into the fire of 'yajna', and consider it as 'yajna'. Some offer the senses such as hearing into the fire of restraint, while others offer the sensual objects such as sound into the fire of the senses.
Gīta Bhāshya 4.25 and 26
The contemplation and worship of the supreme lord itself is 'yajna'. The word 'Yajna' denotes the supreme reality in the form of the lord Bhagavan.
यज्ञभेदान् आह - दैवम् इत्यादिना। दैवं भगवन्तम्। स एव तेषां यज्ञः। भगवदुपासनम् यज्ञम्, इति क्रिया विशेषणम्। नान्यत् तेषाम् अस्ति यतीनां केषाञ्चित्। यज्ञं भगवन्तम्।
Different types of 'yajna' are explained by 'daiva' and such verses. The word 'daivaṁ' refers to 'Bhagavan', the supreme lord. He alone is their 'yajna'. The contemplation and worship of the supreme lord itself is 'yajna'. Such is the speciality of the activity involving contemplation and worship. For some aspiring ascetics, there is no other (path). The word 'Yajna', i.e. sacrifice, itself denotes the supreme reality in the form of the lord Bhagavan.
"यज्ञेन यज्ञम्", "यज्ञो विष्णुर्देवता"
"From Yajna, the sacrifice, attain Yajna, the lord.", "The Yajna is the deity in the form of lord Vishnu."
इत्यादिश्रुतिभ्यः।
- are the Vēdic testimonials.
यज्ञेन प्रसिद्धेनैव। यज्ञं प्रति यज्ञेन जुह्वतीति सर्वत्र समम् "तं यज्ञम्" इत्यादौ। उक्तं च-
By well established and renowned tradition, the word "yajñena" means "by means of sacrifice". The word 'yajñaṁ' is used always to refer to the person, in this case the lord, for whose sake sacrifice is being conducted. Example of "taṁ yajñam" from Purusha sukta (Rig 10.90) is given as an example. It is also said:
"विष्णुं रुद्रेण पशुना ब्रह्मा ज्येष्ठेन सूनुना। अयजन्मानसे यज्ञे पितरं प्रपितामहः॥"
"The great grandfather Brahma worshipped his father Lord Vishnu by offering his eldest son Rudra as sacrifice in his mind."
इति ॥२५,२६॥
- states testimonial.