In plain words
little by little one should become quiet through buddhi held firmly by patience; making manas rest in Ātma, one should think of nothing at all.
Word for word
Slowly, slowly one should come to rest by buddhi held by steadiness; having made the mind abide in the Self, one should not think of anything at all.
शनैः शनैरुपरमेद् बुद्ध्या धृतिगृहीतयाआत्मसंस्थं मनः कृत्वा न किञ्चिदपि चिन्तयेत्
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam· bhāṣya
शनैः शनैः न सहसा उपरमेत् उपरतिं कुर्यात् । कया ? बुद्ध्या । किंविशिष्टया ? धृतिगृहीतया धृत्या धैर्येण गृहीतया धृतिगृहीतया धैर्येण युक्तया इत्यर्थः । आत्मसंस्थम् आत्मनि संस्थितम् ‘आत्मैव सर्वं न ततोऽन्यत् किञ्चिदस्ति’ इत्येवमात्मसंस्थं मनः कृत्वा न किञ्चिदपि चिन्तयेत् । एष योगस्य परमो विधिः ॥ २५ ॥
In plain words
Slowly, slowly—never suddenly—one should let it all settle, bring it to a stop. With what? With the intellect. What kind of intellect? One held steady by steadfastness, by sheer fortitude—that's what's meant. Fix the mind in the Self, resting it there, holding to this: ‘the Self alone is everything; nothing else exists apart from it.’ Having fixed the mind in the Self this way, one shouldn't think of anything else at all. This is the highest rule of yoga.
Close to the Sanskrit
Slowly, slowly, not suddenly, one should withdraw, i.e. should bring about cessation. By what? By the intellect. Qualified by what? By an intellect held by steadfastness—i.e. held by fortitude—‘held by steadfastness’—i.e. endowed with fortitude—that is the meaning. Having made the mind ‘fixed in the Self,’ i.e. situated in the Self, thus: ‘the Self alone is everything; apart from that nothing else whatsoever exists’—having made the mind fixed in the Self in this way, one should not think of anything at all. This is the supreme rule of yoga.