Bhashya
असौ वाव लोको गौतमाग्निरित्यादि ।इह सायं प्रात-रग्निहोत्राहुती हुते पयआदिसाधने श्रद्धापुरःसरे आहवनीया-ग्निसमिद्धूमार्चिरङ्गारविस्फुलिङ्गभाविते कर्त्रादिकारकभावितेच अन्तरिक्षक्रमेणोत्क्रम्य द्युलोकं प्रविशन्त्यौ सूक्ष्मभूते अ-प्समवायित्वादप्शब्दवाच्ये श्रद्धाहेतुत्वाच्च श्रद्धाशब्दवाच्ये ।तयोरधिकरणः अग्निः अन्यच्च तत्संबन्धं समिदादित्युच्यते ।या च असावग्न्यादिभावना आहुत्योः, सापि तथैव निर्दि-श्यते ।असौ वाव लोकोऽग्निः हे गौतम—यथाग्निहोत्राधिकर-णमाहवनीय इह ।तस्याग्नेर्द्युलोकाख्यस्य आदित्य एव स-मित्, तेन हि इद्धः असौ लोको दीप्यते, अतः समिन्ध-नात् समिदादित्यः ।रश्मयो धूमः, तदुत्थानात्; समिधोहि धूम उत्तिष्ठति ।अहरर्चिः प्रकाशसामान्यात्, आदि-त्यकार्यत्वाच्च ।चन्द्रमा अङ्गाराः, अह्नः प्रशमेऽभिव्यक्तेः ;अर्चिषो हि प्रशमेऽङ्गारा अभिव्यज्यन्ते ।नक्षत्राणि विस्फु-लिङ्गाः, चन्द्रमसोऽवयवा इव विप्रकीर्णत्वसामान्यात् ॥
In plain words
That heavenly world itself is a fire, O Gautama. There, the morning and evening oblations—offered with milk and other such means, accompanied by faith, and charged with the qualities of the altar fire's fuel, smoke, flame, embers, and sparks, along with all the agencies of sacrifice—rise up through the intermediate space and enter the heavenly realm. Because they are essentially water and are born of faith, they are known by the names of both water and faith.
Close to the Sanskrit
That indeed world is fire, O Gautama. Here, after the evening and morning oblations are offered with milk and other means accompanied by faith, imbued with the fire's fuel, smoke, flame, ember, and spark, and imbued with agent and other factors, having ascended by the path of the intermediate space, the two subtle oblations enter the heavenly world, being designated by the word water because they consist of water and because of being caused by faith, and being designated by the word faith.