p. 247
‘निष्कल्मषं तपस्त्वेतत्केवलं परिचक्षते’ इति श्रुतस्य तपसः कल्मषं ब्रूहि हे सनत्सुजात, येन निष्कल्मषेण तपसा इदं ब्रह्म गुह्यं सनातनं विद्याम् ॥
In plain words
You said: 'this alone, free of stain, is what they call austerity.' Then tell me the stain in that austerity you spoke of, Sanatsujāta — so that by austerity without stain I may know this Brahman, hidden and eternal.
Close to the Sanskrit
'But this alone, stainless, they call austerity' — of that austerity thus heard, tell the stain, O Sanatsujāta, by which stainless austerity I may know this Brahman, secret, eternal.