In plain words
Let a person lift oneself by oneself; let one not degrade oneself. For the self alone is one's friend, and the self alone is one's enemy.
Word for word
One should lift up oneself by oneself; one should not let oneself sink; for oneself alone [is] one's friend, oneself alone [is] one's enemy.
उद्धरेदात्मनाऽऽत्मानं नाऽऽत्मानमवसादयेत्आत्मैव ह्यात्मनो बन्धुरात्मैव रिपुरात्मनः
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam
यदा एवं योगारूढः, तदा तेन आत्मा उद्धृतो भवति संसारादनर्थजातात् । अतः —
उद्धरेत् संसारसागरे निमग्नम् आत्मना आत्मानं ततः उत् ऊर्ध्वं हरेत् उद्धरेत् , योगारूढतामापादयेदित्यर्थः । न आत्मानम् अवसादयेत् न अधः नयेत् , न अधः गमयेत् । आत्मैव हि यस्मात् आत्मनः बन्धुः । न हि अन्यः कश्चित् बन्धुः, यः संसारमुक्तये भवति । बन्धुरपि तावत् मोक्षं प्रति प्रतिकूल एव, स्नेहादिबन्धनायतनत्वात् । तस्मात् युक्तमवधारणम् ‘आत्मैव ह्यात्मनो बन्धुः’ इति । आत्मैव रिपुः शत्रुः । यः अन्यः अपकारी बाह्यः शत्रुः सोऽपि आत्मप्रयुक्त एवेति युक्तमेव अवधारणम् ‘आत्मैव रिपुरात्मनः’ इति ॥ ५ ॥
In plain words
When you have climbed into yoga like this, then by yourself the self has been pulled clear of saṃsāra, that whole swarming brood of harm. And so —
'One should raise the self by the self,' pull it up out of the ocean it's drowning in, this cycle of birth and death — that's what 'lift up' means, bringing about the state of having ascended in yoga. That's the meaning. 'One should not let the self sink,' should not drag it downward, should not push it down. 'The self alone is the self's friend' — because no other friend can actually free you from this cycle; even a kinsman, in fact, works against liberation, since attachment to kin is exactly the kind of bond that keeps you tied down. So the statement is exactly right: 'the self alone is the self's friend.' And 'the self alone is the enemy' too — any outside enemy who harms you is, in the end, only ever set in motion by the self itself. So this too is exactly right: 'the self alone is the self's enemy.'
Close to the Sanskrit
When one is thus mounted upon yoga, then by him the self becomes lifted out of saṃsāra, which is a brood of ills. Therefore —
'One should uplift the self by the self,' immersed in the ocean of transmigratory existence — from there, 'up,' upward, 'should lift' — [i.e.] 'should uplift,' should bring about the state of having ascended in yoga. That is the meaning. 'Should not let the self sink,' should not lead [it] downward, should not cause [it] to go downward. 'For the self alone, since, is the friend of the self.' For no other friend is there who could bring about liberation from transmigratory existence; even a kinsman, at any rate, is adverse toward liberation, since he is the very basis of bondage through affection and the like. Therefore the assertion, 'the self alone, for, of the self, is the friend,' is correct. 'The self alone is the enemy,' the foe; the other, injurious, external enemy — he too is set in motion by the self alone; so this too is a correct assertion, 'the self alone is the enemy of the self.'