हिरण्मये परे कोशेविरज ब्रह्म निष्कलम् ।तच्छुभ्र ज्योतिषा ज्योति-स्तद्यदात्मविदो विदुः ॥ १० ॥
In plain words
Within the supreme and golden sheath resides the stainless, partless Brahman. Pure, it is the light of lights. This is what the knowers of the Self realize.
Close to the Sanskrit
In the golden, supreme sheath is stainless, partless Brahman. That is pure, the light of lights. That is what the knowers of the Self know.