Mandukya Karika, verse 3.13


जीवात्मनोरनन्यत्वमभेदेन प्रशस्यते ।
नानात्वं निन्द्यते यच्च तदेवं हि समञ्जसम् ॥ १३ ॥

jīvātmanorananyatvamabhedena praśasyate |
nānātvaṃ nindyate yacca tadevaṃ hi samañjasam || 13 ||

13. As the identity of Jīva and Ātman, through their non-dual character, is praised and multiplicity is condemned (in the scriptures), therefore, that (non-duality) alone is rational and correct.

Shankara Bhashya (commentary)

The Śāstras 1 as well as the sages like Vyāsa, etc., extol the identity of Jīva and the Supreme Self through the negation of all differences—the conclusion arrived at by reasoning and supported by the scriptures. Further, the experiences of multiplicity which are natural (to the ignorant) and common to all beings—the view propounded by those who do not understand the real import of the Śāstras and who indulge in futile reasoning—have been condemned2 thus: “But there is certainly nothing corresponding to the dual existence,” “Fear arises from the consciousness of duality,” “If he sees the slightest difference (in Ātman) then he is overcome with fear,” “All this is verily Ātman, “He goes from death to death who sees here (in this Ātman) multiplicity.” Other Knowers of Brahman as well as the scriptures (quoted above) extol identity (of Jīva and Brahman) and condemn multiplicity. Thus alone this praise and condemnation can easily be comprehended; in other words, it accords with reason. But the false views (vainly) advanced by the logicians,3 not easy of comprehension, cannot be accepted as facts (Truth).