Verse
शुचौ देशे प्रतिष्ठाप्य स्थिरमासनमात्मनः ।नात्युच्छ्रितं नातिनीचं चैलाजिनकुशोत्तरम् ॥
śucau deśe pratiṣṭhāpya sthiramāsanamātmanaḥnātyucchritaṃ nātinīcaṃ cailājinakuśottaram
He should set in a pure spot his firm seat, neither too high, nor yet too low, covered with a cloth, with a deer skin, with sacred grass, and there seated with a concentrated mind and with the workings of the mental consciousness and the senses under control, he should practise Yoga for self-purification.
Gītā 6·11