Chapter 2 · The Yoga of Knowledge · Krishna said
Bhagavad Gita 2.41 — A focused mind
व्यवसायात्मिका बुद्धिरेकेह कुरुनन्दन। बहुशाखा ह्यनन्ताश्च बुद्धयोऽव्यवसायिनाम् ॥
vyavasāyātmikā buddhirekeha kurunandana | bahuśākhā hyanantāśca buddhayo'vyavasāyinām ||
Meaning
On this path the mind is firmly set on one aim, Arjuna. But the thoughts of the undecided are scattered and endless.