Sankhya Yoga 2.32

Verse 2.32

यदृच्छया चोपपन्नं स्वर्गद्वारमपावृतम् |

सुखिन: क्षत्रिया: पार्थ लभन्ते युद्धमीदृशम् || 32||

yadṛichchhayā chopapannaṁ swarga-dvāram apāvṛitam

sukhinaḥ kṣhatriyāḥ pārtha labhante yuddham īdṛiśham

yadṛichchhayā—unsought; cha—and; upapannam—has come upon; swarga—celestial abodes; dvāram—door; apāvṛitam—wide open; sukhinaḥ—happy; kṣhatriyāḥ—warriors; pārtha—Arjun, the son of Pritha; labhante—obtain; yuddham—war; īdṛiśham—such

O Partha, happy are the warriors to whom such opportunities to defend righteousness come unsought, opening for them are the doors to the celestial abodes.

The fruits of doing one’s duty

As per the Dharma shastra, one meets with the results of either his right or wrong actions. Based on the vision of shastra, there are two kinds of results of any action . Drushta phalam is the result of action that is visible to everyone. The invisible action is called the adrushta phalam. This kind of invisible result is promised by the shastra and one can only trust its words as there is no way to prove them. One has to simply perform his duties with trust and the invisible result follows. One such trust is, if one performs his duty properly he will enter heaven after death.

Yadruchaya means unexpected, unsought. Krishna says, for Arjuna the doors of heaven have been unexpectedly open by way of this war. Only fortunate kshatriyas will get this kind of an opportunity. 

For everyone, very rarely in their lives, this kind of unexpectedly good time will come knocking  at their doors. One must make use of it in order to be successful in life. Only those who know how to use these opportunities attain fame and name. Krishna further explains what would happen if this golden opportunity is not used properly.