Bhagavad Gita - Chapter 6, Verse 24, 25.
मनसैवेन्द्रियग्रामं विनियम्य समन्तत: || 24||
शनै: शनैरुपरमेद्बुद्ध्या धृतिगृहीतया |
आत्मसंस्थं मन: कृत्वा न किञ्चिदपि चिन्तयेत् || 25||
manasaivendriya-grāmaṁ viniyamya samantataḥ
śhanaiḥ śhanair uparamed buddhyā dhṛiti-gṛihītayā
ātma-sansthaṁ manaḥ kṛitvā na kiñchid api chintayet
Some English translations (verse 25):
(1 - Prabhupada)
(2 - Fuerstein)
Making the mind settled in the Self by holding the wisdom-faculty steadfast, he should not think of anything.
(3 - Muktananda)
Completely renouncing all desires arising from thoughts of the world, one should restrain the senses from all sides with the mind. Slowly and steadily, with conviction in the intellect, the mind will become fixed in God alone, and will think of nothing else.
(4 - Sri Ramana Maharshi)
Fix the mind [your attention] in [or on] ātman [yourself]; do not think even the slightest of anything else at all.