“This is never to be spoken by you to one without austerity, nor to one without devotion, nor to one who does not wish to hear, nor to one who cavils at Me (mām abhyasūyati)” (18.67). The teaching is guarded not by secrecy for its own sake but by fitness — it cannot be received by the carping, the faithless or the unwilling (recall 9.1, “to you who do not cavil”). But to the fit it must be given freely: “he who, with supreme devotion to Me, teaches this deepest secret to My devotees, shall doubtless come to Me; none among men does dearer service to Me than he” (18.68–69). And the rewards of engaging it are graded generously (18.70–71): he who studies this dialogue worships Him by the “sacrifice of knowledge” (jñāna-yajña); and even he who merely hears it with faith and without cavil is freed, and attains the auspicious worlds of the righteous. Thus the teaching is at once protected from the scoffer and offered to everyone sincere — even the humble listener is not left out.