This gospel is never to be instructed to one who is not austere, is not a devotee, does not want to listen to these words, or who envies Me (the Supreme).
Krishna has completed his exposition. Any instruction a Teacher gives has its basic relevance and applicability. Krishna’s last words of wholesome surrender, refuge, are not a blanket sanction to do whatever one wishes. They are specifically meant for one like Arjuna, who has sought refuge under Krishna seeking supreme good (sreyas), and who embodies unconditional faith in what Krishna imparts (2.7). To such a one, the last two verses are a full nectar.
But what about rest of the people? Krishna is firm to deny transmission of his words to the undeserving. Arjuna was a seeker of sreyas, the ultimate good, felicity. What Krishna said is the real means for him, not for others.
Thus Krishna warns that his instruction is not to be imparted to those who lack the requisite austerity, devotion and willingness to hear, and who are judgemental about or despise what they hear. What a great caution!