6.27

प्रशान्तमनसं ह्येनं योगिनं सुखमुत्तमम् ।
उपैति शान्तरजसं ब्रह्मभूतमकल्मषम् ॥

praśāntamanasaṃ hy enaṃ yoginaṃ sukham uttamam
upaiti śāntarajasaṃ brahmabhūtam akalmaṣam

Kṛṣṇa (कृष्ण) is still speaking.

The verse

The highest happiness comes to this yogin whose mind is at peace, whose restless drive has gone quiet, who has become brahman, who is without stain.

नेपालीमा

मन शान्त भएको, चञ्चल जोश शान्त भएको, ब्रह्म बनेको, कलङ्करहित यस योगीकहाँ सर्वोच्च सुख आउँछ।

Where it sits

The bringing-back of 6.26 has a fruit. Happiness comes to him. It is not something he manufactures in the next verse's formula. 6.28 will say the same attainment as the touch of brahman (ब्रह्मन्).

Split: प्रशान्त-मनसम् + हि + एनम् + योगिनम् + सुखम् + उत्तमम् + उपैति + शान्त-रजसम् + ब्रह्म-भूतम् + अकल्मषम्

praśānta-manasam + hi + enam + yoginam + sukham + uttamam + upaiti + śānta-rajasam + brahma-bhūtam + akalmaṣam

Sanskrit, in depth

The words

देवनागरीWordGrammarSense
प्रशान्त-मनसम्praśānta-manasamaccusative singularwhose mind is at peace. Agrees with yoginam (योगिनम्).
हिhiindeclinableindeed.
एनम्enamaccusative singularthis.
योगिनम्yoginamaccusative singularthe yogin.
सुखम्sukhamnominative singularhappiness. Neuter nominative.
उत्तमम्uttamamnominative singularhighest. Agrees with sukham (सुखम्).
उपैतिupaitipresent, 3rd singularcomes to, approaches. उप-इ upa-i.
शान्त-रजसम्śānta-rajasamaccusative singularwhose rajas (रजस्), the driving restlessness, has gone quiet.
ब्रह्म-भूतम्brahma-bhūtamaccusative singularwho has become brahman (ब्रह्मन्).
अकल्मषम्akalmaṣamaccusative singularstainless.

The phrases

सुखम् उत्तमम् उपैति sukham uttamam upaiti is the event. The highest happiness comes. The accusatives are who it comes to: this yogin.

praśāntamanasam (प्रशान्तमनसम्), śāntarajasam (शान्तरजसम्), brahmabhūtam (ब्रह्मभूतम्), and akalmaṣam (अकल्मषम्) all agree with enam yoginam (एनम् योगिनम्). Peaceful in mind, the drive gone quiet, become brahman (ब्रह्मन्), without stain.

hi enam (हि एनम्) is hyenam (ह्येनम्). सुखम् उत्तमम् sukham uttamam is sukhamuttamam (सुखमुत्तमम्).

Sanskrit in this line

upaiti (उपैति) takes the accusative of the person approached. The happiness is nominative, the subject, even though neuter sukham (सुखम्) looks like an accusative. You tell them apart by the verb and by yoginam (योगिनम्), which is visibly accusative. The happiness comes to the yogin. The yogin does not come to the happiness.

Say it back

What comes, and to whom. If the yogin is made the subject, "he approaches happiness," the accusative yoginam (योगिनम्) has been misread.