Bhashya
अथ यदनाशकायनमित्याचक्षते, ब्रह्मचर्यमेव तत् ।यमात्मानं ब्रह्मचर्येण अनुविन्दते, स एष हि आत्माब्रह्मचर्यसाधनवतो न नश्यति; तस्मादनाशकायनमपि ब्र-ह्मचर्यमेव ।अथ यदरण्यायनमित्याचक्षते, ब्रह्मचर्यमेवतत् ।अरण्यशब्द्योरर्णवयोर्ब्रह्मचर्यवतोऽयनादरण्यायनं ब्र-ह्मचर्यम् ।यो ज्ञानायज्ञः एषणादिष्टं सतस्त्राणात्सत्रायणंमननान्मौनम् अनशनादनाशकायनम् अरण्ययोर्गमनादर-ण्यायनम् इत्यादिभिर्महद्भिः पुरुषार्थसाधनैः स्तुतत्वात् ब्रह्म-चर्यं परमं ज्ञानस्य सहकारिकारणं साधनम्-इत्यतो ब्रह्म-विदा यत्नतो रक्षणीयमित्यर्थः ।तत् तत्र हि ब्रह्मलोकेअरश्च ह वै प्रसिद्धौ ण्यश्च अर्णवौ समुद्रौ समुद्रोपमे वासरसी, तृतीयस्यां भुवमन्तरिक्षं च अपेक्ष्य तृतीया द्यौःतस्यां तृतीयस्याम् इतः अस्माल्लोकादारभ्य गण्यमानायांदिवि ।तत् तत्रैव च ऐरम् इरा अन्नं तन्मयः ऐरः मण्डःतेन पूर्णम् ऐरं मदीयं तदुपयोगिनां मदकरं हर्षोत्पादकंसरः ।तत्रैव च अश्वत्थो वृक्षः सोमसवनो नामतः सोमो-ऽमृतं तन्निस्स्रवः अमृतस्रव इति वा ।तत्रैव च ब्रह्मलोकेब्रह्मचर्यसाधनरहितैर्ब्रह्मचर्यसाधनवद्भ्यः अन्यैः न जीयत इति अपराजिता नाम पूः पुरी ब्रह्मणो हिरण्यगर्भस्य ।ब्रह्मणा च प्रभुणा विशेषेण मितं निर्मितं तच्च हिरण्मयं सौवर्णं प्रभुविमितं मण्डपमिति वाक्यशेषः ॥
In plain words
Now, whatever is called the 'path of non-fasting' is simply spiritual discipline. The Self which is found through this discipline does not perish for one who is established in it; therefore, the path of non-fasting is truly spiritual discipline itself. Likewise, what is called the 'path of the forest' is also spiritual discipline. Because it is praised through great means of human fulfillment—such as the sacrifice of knowledge, the protective session, silence born of deep reflection, the path of non-fasting, and journeying into the forests—spiritual discipline is the supreme supporting instrument of knowledge. Therefore, the knower of Brahman must guard it with all diligence. In that very world of Brahman are the two well-known celestial lakes, Ara and Nya, located in the third heaven beyond this earth. There too is the lake Aira, filled with the essence of food, bringing joy to those who partake of it. There stands the divine pipal tree named Somasavana, which oozes the nectar of immortality. And in that world of Brahman is the invincible city of Hiranyagarbha, which cannot be conquered by those who lack spiritual discipline, but belongs to those who possess it—a golden pavilion fashioned and measured by the supreme Lord himself.
Close to the Sanskrit
Now that which they speak of as 'anāśakāyana', that is brahmacharya indeed. That Self which they discover through brahmacharya, that soul possessing brahmacharya discipline does not perish; therefore 'anāśakāyana' is also brahmacharya indeed. Now that which they speak of as 'araṇyāyana', that is brahmacharya indeed. Araṇyāyana is brahmacharya through the going to the forest by one possessing brahmacharya from the words araṇya and arṇava. Because it is praised by great human-goal means such as the sacrifice of knowledge, session-performance through protection from beings, silence from reflection, non-fasting path from non-eating, forest path from going to forests, brahmacharya is the supreme auxiliary cause and instrument of knowledge—hence it is to be guarded with effort by the knower of Brahman, is the meaning. There indeed in that Brahma-loka, Ara and Nya are well-known two oceans or ocean-like lakes, regarding the third heaven counting from this earth here as the third. There indeed is also Airam, whose essence is food, Aira, filled with that, the intoxicating or joyful lake for those who use it. There indeed is also the tree named Somasavana, the pipal tree, Soma being immortality, its exudation or nectar-secretion. And there in Brahma-loka, Aparajita is the name of the city of Brahma, Hiranyagarbha, which is not conquered by others who are devoid of brahmacharya-discipline, by those possessing it. And measured, constructed specifically by the lord Brahma, and that is a golden, golden, lord-measured pavilion—such is the remainder of the sentence.