Mandukya Karika, verse 3.39
अस्पर्शयोगो वै नाम दुर्दर्शः सर्वयोगिभिः ।
योगिनो बिभ्यति ह्यस्मादभये भयदर्शिनः ॥ ३९ ॥
asparśayogo vai nāma durdarśaḥ sarvayogibhiḥ |
yogino bibhyati hyasmādabhaye bhayadarśinaḥ || 39 ||
39. This Yoga, which is not in touch with anything, is hard to be attained by all Yogis (in general). The Yogis are afraid of it, for they see fear in it where there is really fearlessness.
Shankara Bhashya (commentary)
Though1 such is the nature of the knowledge of the Supreme Reality, yet it is described in the Upaniṣads2 as Yoga not in touch with anything; for, it is free from all touch implying relations (with objects). It is hard to be attained by the Yogis 3 who are devoid of the knowledge taught in the Vedānta philosophy. In other words, this truth can be realised only by the efforts culminating in the knowledge of Ātman as the Sole Reality. The Yogis shrink from it, which is free from all fear, for4 they think that this Yoga brings about the annihilation of their self. In other words, the Yogis, being devoid of discrimination, who, through fear, apprehend the destruction of their self, are afraid of it which is, in reality, fearlessness.5