4.39

श्रद्धावाँल्लभते ज्ञानं तत्परः संयतेन्द्रियः ।
ज्ञानं लब्ध्वा परां शान्तिमचिरेणाधिगच्छति ॥

śraddhāvāṃl labhate jñānaṃ tatparaḥ saṃyatendriyaḥ
jñānaṃ labdhvā parāṃ śāntim acireṇādhigacchati

Kṛṣṇa (कृष्ण) is still speaking, to Arjuna.

The verse

The faithful man, intent on that, with his senses held, obtains knowledge; having obtained it, he reaches the highest peace before long.

नेपालीमा

श्रद्धालु, त्यसमा लागेको, इन्द्रिय वशमा राखेको मानिस ज्ञान पाउँछ। पाएपछि ऊ धेरै बेर नलाग्दै परम शान्तिमा पुग्छ।

Where it sits

4.38 said the completed yogin finds knowledge in the self, in time, and this verse names the way to it: faith, intent, held senses, and then peace, not delayed. 4.40 names the man who has none of this, and what he loses.

Split: श्रद्धावान् + लभते + ज्ञानम् + तत्-परः + संयत-इन्द्रियः + ज्ञानम् + लब्ध्वा + पराम् + शान्तिम् + अचिरेण + अधिगच्छति

śraddhāvān + labhate + jñānam + tat-paraḥ + saṃyata-indriyaḥ + jñānam + labdhvā + parām + śāntim + acireṇa + adhigacchati

Sanskrit, in depth

The words

देवनागरीWordGrammarSense
श्रद्धावान्śraddhāvānnominativeone who has faith. śraddhā (श्रद्धा) plus the possessive --vant (वन्त्).
लभतेlabhatepresent, 3rd singular, middlehe obtains. From labh (लभ्).
ज्ञानम्jñānamaccusativeknowledge.
तत्-परःtat-paraḥnominative, bahuvrīhi (बहुव्रीहि)one whose highest aim is that. para (पर) here is the utmost.
संयत-इन्द्रियःsaṃyata-indriyaḥnominative, bahuvrīhi (बहुव्रीहि)one whose senses are held. saṃyata (संयत) is "restrained," from sam-yam (सम्-यम्).
ज्ञानम्jñānamaccusativeknowledge.
लब्ध्वाlabdhvāgerundhaving obtained.
पराम्parāmaccusative femininehighest. Agrees with śāntim (शान्तिम्).
शान्तिम्śāntimaccusativepeace.
अचिरेणacireṇainstrumental singularin no long time, before long. cira (चिर) is "long." The instrumental is the measure of time.
अधिगच्छतिadhigacchatipresent, 3rd singularhe reaches, he attains. From adhi-gam (अधि-गम्).

The phrases

śraddhāvān labhate jñānaṃ tatparaḥ saṃyatendriyaḥ (श्रद्धावान् लभते ज्ञानं तत्परः संयतेन्द्रियः) is who obtains it. The man of faith, intent on that, his senses held, obtains knowledge. Three nominatives, one verb. śraddhāvān labhate (श्रद्धावान् लभते) is recited śraddhāvāṃl labhate (श्रद्धावाँल्लभते).

ज्ञानं लब्ध्वा परां शान्तिम् अचिरेण अधिगच्छति jñānaṃ labdhvā parāṃ śāntim acireṇa adhigacchati is what follows the obtaining. Having obtained knowledge, he reaches the highest peace before long. शान्तिम् अचिरेण śāntim acireṇa is śāntim acireṇa (शान्तिमचिरेण). acireṇa adhigacchati (अचिरेण अधिगच्छति) is acireṇādhigacchati (अचिरेणाधिगच्छति).

Sanskrit in this line

śraddhāvān (श्रद्धावान्) before l (ल्) does not stay a plain n (न्). The n (न्) becomes the candrabindu, and the l (ल्) is doubled: śraddhāvāṃl labhate (श्रद्धावाँल्लभते). The mark ँ is that nasal. It is not a vowel and not a separate word. The split is still श्रद्धावान् + लभते śraddhāvān + labhate. Read the doubled l (ल्) as the meeting, the way tāṃs tathā (तांस्तथा) in 4.11 was a meeting of n (न्) and t (त्).

Say it back

Who obtains knowledge, and what he reaches after it. If śraddhāvān (श्रद्धावान्) is pronounced with a bare n (न्) and a single l (ल्), stay on the join until the candrabindu and the double l (ल्) are both there.