Shiva Purana
तुरीया देवि भूतानां योगिनां ध्यानिनां तथा ॥ सुखासने यथास्थानं योगी नियतमानसः ॥ २८॥
The fourth, O Devi, is the fourth of all beings, the yogis and the meditators. The yogi should sit in a comfortable seat with a fixed mind.
english translation
turIyA devi bhUtAnAM yoginAM dhyAninAM tathA ॥ sukhAsane yathAsthAnaM yogI niyatamAnasaH ॥ 28॥
hk transliteration by Sanscript