What people call sacrifice (yagña), that is really abstinence (brahmakarya). For he who knows, obtains that (world of Brahman, which others obtain by sacrifice), by means of abstinence. What people call sacrifice (ishta), that is really abstinence, for by abstinence, having searched (ishtvâ), he obtains the Self.

In plain words: What people call religious sacrifice is really self-discipline, or brahmacharya. Through disciplined living, a wise person reaches what others hope to gain by rituals, and finds the Self.