Verse 2.68

तस्माद्यस्य महाबाहो निगृहीतानि सर्वशः। इन्द्रियाणीन्द्रियार्थेभ्यस्तस्य प्रज्ञा प्रतिष्ठिता।।2.68।।

tasmād yasya mahā-bāho nigṛihītāni sarvaśhaḥ indriyāṇīndriyārthebhyas tasya prajñā pratiṣhṭhitā

Meaning

So, Arjuna, my dude, the person who's got their senses totally under control? Their knowledge is straight fire.

Commentary

Yo, when you totally control your senses, your mind doesn't go wild chasing every little thing. It's chill, like a lamp in a room with no breeze. You're all about that inner peace, and your knowledge is on point. (See 3.7)