Ch 18, Sh 57-61, Bhagawad Gita, Shankar Bhashya

Cetasa, mentally, with a discriminating intellect; sannyasya, surrendering; sarva-karmani, all actions meant for seen or unseen results; mayi, to Me, to God, in the manner described in, 'Whatever you do, whatever you eat' (9.27); and matparah, accepting Me as the supreme-you to whom I, Vasudeva, am the supreme, are matparah; becoming so; satatam, ever; maccittah bhava, have your kind fixed only on Me; upasritya, by resorting-resorting implies not taking recourse to anything else; buddhi-yogam, to the concentration of your intellect. Having the intellect (buddhi) concentrated on Me is buddhi-yoga.
Maccittah, having your mind fixed on Me; tarisyasi, you will cross over; sarva-durgani, all difficulties, all causes of transmigration which are difficult to overcome; mat-prasadat, through My grace. Atha cet, if, on the other hand; tvam, you; na srosyasi, will not listen to, will not accept, My words; ahankarat, out of egotism, thinking 'I am learned'; then vinanksyasi, you will get destroyed, will court ruin.
And this should not be thought of by you 'I am independent. Why should I follow another's bidding?'
Yat, that; manyase, you think, resolve; this 'na yotsye, I shall not fight'; asritya, by relying; on ahankaram, egotism, mithya, vain; is esah, this; vyava-sayah, determination; te, of yours; because prakrtih, nature, your own nature of a Ksatriya; niyoksyati, will impell; ;tvam, you!
And because of nibaddhah, being securely bound; svena, by your own; karmana, duty; svabhavajena, born of nature herosim etc. as stated (in 43); O son of Kunti, you avasah, being helpless, under another's control; karisyasi api, will verily do; tat, that duty; yat, which duty; you na, do not; icchasi, wish; kartum, to do; mohat, owing to indiscrimination.
For,
Arjuna, O Arjuna-one whose self is naturally white (pure), i.e. one possessing a pure internal organ. This follows from the Vedic text, 'The day is dark and the day is arjuna (white) (Rg. sam. 6.9.1). Isvarah, the Lord , Narayana the Ruler; tisthati, resides, remains seated; hrd-dese, in the region of the heart; sarva-bhutanam, of all creatures, of all living beings.