In plain words
Whatever action a person undertakes through body, speech, and manas, whether right or contrary, these five are its causes.
Word for word
Whatever action a person undertakes with body, speech and manas, right or contrary, these five are its causes.
शरीरवाङ्मनोभिर्यत् कर्म प्रारभते नरःन्याय्यं वा विपरीतं वा पञ्चैते तस्य हेतवः
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam
शरीरवाङ्मनोभिः यत् कर्म त्रिभिः एतैः प्रारभते निर्वर्तयति नरः, न्याय्यं वा धर्म्यं शास्त्रीयम् , विपरीतं वा अशास्त्रीयम् अधर्म्यं यच्चापि निमिषितचेष्टितादि जीवनहेतुः तदपि पूर्वकृतधर्माधर्मयोरेव कार्यमिति न्याय्यविपरीतयोरेव ग्रहणेन गृहीतम् , पञ्च एते यथोक्ताः तस्य सर्वस्यैव कर्मणो हेतवः कारणानि ॥
ननु एतानि अधिष्ठानादीनि सर्वकर्मणां निर्वर्तकानि । कथम् उच्यते ‘शरीरवाङ्मनोभिः यत् कर्म प्रारभते’ इति ? नैष दोषः ; विधिप्रतिषेधलक्षणं सर्वं कर्म शरीरादित्रयप्रधानम् ; तदङ्गतया दर्शनश्रवणादि च जीवनलक्षणं त्रिधैव राशीकृतम् उच्यते शरीरादिभिः आरभ्यते इति । फलकालेऽपि तत्प्रधानैः साधनैः भुज्यते इति पञ्चानामेव हेतुत्वं न विरुध्यते इति ॥ १५ ॥
In plain words
Whatever action a person undertakes and carries out through these three means — body, speech, and mind — is either proper, righteous, and scripturally sanctioned, or its opposite, unsanctioned and unrighteous. And as for things like blinking or other involuntary movements, simply necessary for staying alive — even those trace back to merit and demerit accumulated earlier; they are already covered once we've named 'the proper' and 'its opposite', so no separate category is needed. These five factors, as already described, are the causes — the causal factors — behind absolutely every action there is.
One might object: didn't you just say the substratum and the other factors — all five — are what accomplish every action? Then how can the verse say 'whatever action one undertakes by body, speech, and mind', mentioning only three? There's no real flaw here. Every action governed by scriptural injunction and prohibition is fundamentally headed by that triad — body, speech, mind — and other activities like seeing and hearing, which are simply features of being alive, get folded into that same threefold grouping as its subordinate parts. That is the sense in which the verse says action 'is undertaken by the body and the rest'. And even later, when the fruit is experienced, it too is experienced through means headed by that same triad. So the causality of all five factors together is not actually contradicted by this threefold way of speaking.
Close to the Sanskrit
Whatever action a man undertakes, carries out, by these three, by body, speech, and mind — whether proper, righteous, scripturally sanctioned, or the opposite, not scripturally sanctioned, unrighteous — and whatever too, such as blinking, involuntary movement, and so on, a cause necessary for living, that too is indeed only the effect of merit and demerit done previously; by the inclusion of only the proper and the opposite, this too is already included. These five, as previously stated, are the causes, the causal factors, of every action whatsoever.
Now, these, the substratum and the rest, are the accomplishing-factors of all actions. How then is it said, 'by body, speech, and mind, whatever action one undertakes' — thus? This is not a flaw; all action, characterized by injunction and prohibition, has as its principal factors the triad beginning with the body; by virtue of being subordinate parts of that, seeing, hearing, and so on, characterized as belonging to living, are said, grouped strictly into three — 'is undertaken by the body and the rest' — thus. Even at the time of the fruit, it is experienced by means principally consisting of that same triad — thus, the causality of the five alone is not contradicted — thus.