Shiva Purana
यथा दीपो निवातस्थः स्पन्दते न कदाचन ॥ तथा समाधिनिष्ठो ऽपि तस्मान्न विचलेत्सुधीः ॥ ६६ ॥
Just as the lamp in a windless spot never flickers so also is the Yogin who is Samādhistha, An intelligent man shall not swerve. He shall be steady.
english translation
yathA dIpo nivAtasthaH spandate na kadAcana ॥ tathA samAdhiniSTho 'pi tasmAnna vicaletsudhIH ॥ 66 ॥
hk transliteration by Sanscript