One verse

Bhagavad Gita 6.26

6.26

यतो यतो निश्चरति मनश्चञ्चलमस्थिरम् | ततस्ततो नियम्यैतदात्मन्येव वशं नयेत् ||६-२६||

yato yato niścarati manaścañcalamasthiram . tatastato niyamyaitadātmanyeva vaśaṃ nayet ||6-26||

yataḥ yataḥ
wherever
niścalati
becomes verily agitated
manaḥ
the mind
cañcalam
flickering
asthiram
unsteady
tataḥ tataḥ
from there
niyamya
regulating
etat
this
ātmani
in the Self
eva
certainly
vaśam
control
nayet
must bring under

From wherever the mind wanders due to its flickering and unsteady nature, one must certainly withdraw it and bring it back under the control of the Self.