Chapter IV Sloka 31

y}izam&t-ujae yaiNt snatnm!,
nay< laekae=STyy}Sy ktae=Ny> ksm.

yajaimtabhujo ynti 
brahma santanam | 
nya loko'styayajasya 
kuto'nya kurusattama ( 4|31)||

Those who eat the remnants of the sacrifice, which are like nectar, go to the eternal Brahman. This world is not for the man who does not perform sacrifice; how then can he have the other, O Arjuna?
Commentary: They go to the eternal Brahman in course of time after attaining the knowledge of the Self through purification of the mind by performing the above sacrifices. He who does not perform any of these is not fit even for this miserable world. How then can he hope to get a better world than this? ( Cf. III. 13)

Chinmayananda:

"remnants of the sacrifice" means "the result of the above mentioned twelve types of Yagnas." The result is a greater amount of self-control and the consequent inner integration of the individual personality. Such an integrated person can gain greater inner poise in meditations through which he/she can easily come to experience the Infinite and the Eternal indicated by the term Brahman. In the second half of the sloka, Krishna wonders how a seeker could hope to achieve the highest without any conscious efffort in perfecting and gaining it.