Vivekachudamani
http://www.sankaracharya.org/vivekachudamani6.php#1
522. From the perception of unreal things there is neither satisfaction nor a cessation of misery. Therefore, being satisfied with the realisation of the Bliss Absolute, the One without a second, live happily in a state of identity with that Reality.
523. Beholding the Self alone in all circumstances, thinking of the Self, the One without a second, and enjoying the Bliss of the Self, pass thy time, O noble soul !
524. Dualistic conceptions in the Atman, the Infinite Knowledge, the Absolute, are like imagining castles in the air. Therefore, always identifying thyself with the Bliss Absolute, the One without a second, and thereby attaining Supreme Peace, remain quiet.
525. To the sage who has realised Brahman, the mind, which is the cause of unreal fancies, becomes perfectly tranquil. This verily is his state of quietude, in which, identified with Brahman, he has constant enjoyment of the Bliss Absolute, the One without a second.
526. To the man who has realised his own nature, and drinks the undiluted Bliss of the Self, there is nothing more exhilarating than the quietude that comes of a state of desirelessness.
527. The illumined sage, whose only pleasure is in the Self, ever lives at ease, whether going or staying, sitting or lying, or in any other condition.--