The Hatha Yoga Pradipika is the classical guide to yoga, written down in the seventeenth century from various ancient sources.
It has four chapters. The following verses are taken from Chapter 4.
(29)The mind is the lord of the [senses]. Prana is the lord of the mind. Laya (absorption) is the lord of the prana, and that laya depends on the nada (the inner sounds).
(30) This itself (the quiescence of the mind) may be called moksha, though others say that it is not. However, when the prana and the manas (mind) have been absorbed, an indefinable joy ensues.
(31) A yogi who has suspended inspirations and expirations, whose senses have become inactive or insensible, whose mental activity has ceased, and whose emotions of the mind have become quiet, obtains success in Laya Yoga.
(58) The external universe is created by our thoughts, as also the imaginary world. Having abandoned the idea of permanency in these creations of thought, and concentrating your mind upon that which is not subject to any changes (i.e. Brahman), O Rama, obtain everlasting and certain peace.