Shvetashvatara Upanishad 2.10

In a clean level spot,

free from pebbles, fire and gravel,

Delightful by its sounds,

its water and bowers,

Favourable to thought,

not offensive to the eye,

In a hidden retreat protected from the wind,

One should practice Yoga.

~ Shvetashvatara Upanishad 2.10 Translated by Paul Deussen