Bhagavad Gita
6.11

शुचौ देशे प्रतिष्ठाप्य स्थिरमासनमात्मनः । नात्युच्छ्रितं नातिनीचं चैलाजिनकुशोत्तरम् ॥

śucau deśe pratiṣṭhāpya sthiramāsanamātmanaḥ | nātyucchritaṃ nātinīcaṃ cailājinakuśottaram ||

Translation

In a clean spot, having established a firm seat for oneself — neither too high nor too low — covered with cloth, deerskin, and kusha grass —

Interpretation

Krishna provides detailed instruction on the meditation seat (asana). The place should be clean (shuchu — pure, uncontaminated). The seat should be stable (sthiram) — not so high as to risk falling, not so low as to invite dampness from the earth. The traditional seat consists of three layers: kusha grass (insulating, sacred), deerskin (traditional material with specific grounding properties), and cloth (for comfort). The physical preparation of the seat reflects the care given to the inner preparation of the mind.