Bhagavad Gita 6.19 Chapter 6, Verse 19

यथा दीपो निवातस्थो नेङ्गते सोपमा स्मृता ।
योगिनो यतचित्तस्य युञ्जतो योगमात्मनः ॥६.१९॥

yathā dīpo nivātastho neṅgate sopamā smṛtā
yogino yatacittasya yuñjato yogamātmanaḥ

Meaning

As a lamp in a windless place does not flicker — that is the image of the yogi of controlled mind, absorbed in meditation on the Self.

Newly written by Bhajan Dhun — scholarly review in progress.

Reference: Bhagavad Gita 6.19 (Chapter 6, The Yoga of Meditation (Atma Samyama Yoga), Verse 19)