BhG 16.21

syntax

kāmaḥ (desire) krodhaḥ (anger) tathā (as well) lobhaḥ [iti] (greed)
narakasya (of hell) idam tri-vidham dvāram (this gate of three parts) ātmanaḥ nāśanam (destruction of the self) [asti] (it is).
tasmāt (therefore) etat trayam (this three) tyajet (he should abandon).

grammar

tri-vidham	–	tri-vidha 1n.1 n. – threefold, of three parts (from: tri – three; vi-√dhā – to divide, vidhā – division, part);
narakasya	–	naraka 6n.1 m. – of hell;
idam	–	idam 1n.1 n. – this;
dvāram	–	dvāra 1n.1 n. – gate, entrance, passage;
nāśanam	–	nāśana 1n.1 n. – destruction, removal (from: √naś – to destroy, to vanish, nāśa – destruction, loss);
ātmanaḥ	–	ātman 6n.1 m. – of the self;
kāmaḥ	–	kāma 1n.1 m. – wish, desire, pleasure (from: √kam –to wish, to love, to long for);
krodhaḥ	–	krodha 1n.1 m. – anger, wrath (from: √krudh – to be angry);
tathā	–	av. – in that manner, so, in like manner;
lobhaḥ	–	lobha 1n.1 m. – greed, covetousness (from: √lubh – to be greedy);
tasmāt	–	av. – therefore (from: tat sn. 5n.1 m. – from that);
etat	–	etat sn. 2n.1 n. – this;
trayam	–	traya 2n.1 n. – triad (from: tri – three);
tyajet	–	√tyaj (to abandon, to give up) Pot. Ā 1v.1 – he should abandon;

textual variants

narakasyedaṁ → narakasyaitad (this of hell);
nāśanam → nāśakam (destroyer);
kāmaḥ krodhas → kāma-krodhas (desire, anger);
tyajet → tyaja (you must abandon);

Śāṃkara

sarvasyā āsuryāḥ saṃpadaḥ saṃkṣepo’yam ucyate, yasmin trividhe sarvaḥ āsurīsaṃpadbhedo’nanto’py antarbhavati | yatparihāreṇa parihṛtaś ca bhavati, yat mūlaṃ sarvasyānarthasya, tat etad ucyate—

trividhaṃ triprakāraṃ narakasya prāptāv idaṃ dvāraṃ nāśanam ātmanaḥ, yat dvāraṃ praviśanneva naśyati ātmā | kasmaicit puruṣārthāya yogyo na bhavatītyetat, atar ucyate dvāraṃ nāśanam ātmanaḥ iti | kiṃ tat ? kāmaḥ krodhas tathā lobhaḥ | tasmāt etat trayaṃ tyajet | yataḥ etat dvāraṃ nāśanam ātmanas tasmāt kāmāditrayametat tyajet

Rāmānuja

asyāsurasvabhāvasyātmanāśasya mūlahetum āha
asyāsurasvabhāvarūpasya narakasyaitat trividhaṃ dvāram, tac cātmano nāśanam; kāmaḥ krodho lobha iti trayāṇāṃ svarūpaṃ pūrvam eva vyākhyātam / dvāram mārgaḥ; hetur ityarthaḥ / tasmād etattrayaṃ tyajet; tasmād atighoranarakahetutvāt kāmakrodhalobhānām, etattritayaṃ dūrataḥ parityajet

Śrīdhara

uktānām āsura-doṣāṇāṃ madhye sakala-doṣa-mūla-bhūtaṃ doṣa-trayaṃ sarvathā varjanīyam ity āha trividham iti | kāmaḥ krodho lobhaś ceti idaṃ trividhaṃ narakasya dvāram | ata evātmano nāśanaṃ nīcayoni-prāpakam | tasmād etat trayaṃ sarvātmanā tyajet

Madhusūdana

nanv āsurī sampad ananta-bhedavatī kathaṃ puruṣāyuṣeṇāpi parihartuṃ śakyaitetvāśaṅkya tāṃ saṅkṣipyāha trividham iti | idaṃ trividhaṃ tri-prakāraṃ narakasya prāptau dvāraṃ sādhanaṃ sarvasyā āsuryāḥ sampado mūla-bhūtam ātmano nāśanaṃ sarva-puruṣārthāyogyatā-sampādanenātyantādhama-yoni-prāpakam | kiṃ tat ? ity ata āha kāmaḥ krodhas tathā lobha iti | prāg vyākhyātam | yasmād etat trayam eva sarvānartha-mūlaṃ tasmād etat trayaṃ tyajet | etat-traya-tyāgenaiva sarvāpy āsurī sampat tyaktā bhavati | etat-traya-tyāgaś cotpannasya vivekena kārya-pratibandhaḥ | tataḥ paraṃ cānutpattir iti draṣṭavyam

Viśvanātha

tad evam āsurīḥ samapttīr vistārya proktā itas tataḥ sādhūktam mā śucaḥ sampadaṃ daivīm abhijāto ‚si bhārata iti | kiṃ vāsurāṇām etat trikam eva svābhāvikam ity āha trividham iti

Baladeva

nanv āsurīṃ prakṛtiṃ naraka-hetuṃ śrutvā ye manuṣyās tāṃ parihartum icchanti | taiḥ kim anuṣṭheyam iti cet tatrāha trividham iti | etat-traya-parihāre tasyāḥ parihāraḥ syād ity arthaḥ