Bhagavad Gita 6.26 Chapter 6, Verse 26

यतो यतो निश्चरति मनश्चञ्चलमस्थिरम् ।
ततस्ततो नियम्यैतदात्मन्येव वशं नयेत् ॥६.२६॥

yato yato niścarati manaścañcalamasthiram
tatastato niyamyaitadātmanyeva vaśaṃ nayet

Meaning

Wherever the restless, unsteady mind wanders, one should draw it back from there and bring it under the control of the Self.

Newly written by Bhajan Dhun — scholarly review in progress.

Reference: Bhagavad Gita 6.26 (Chapter 6, The Yoga of Meditation (Atma Samyama Yoga), Verse 26)