Krishna immediately adds the critical caveat to the previous verse. Yes, you must perform charity, sacrifice, and penance (etāny api tu karmāṇi), BUT they must be performed after completely giving up all psychological attachment to them (saṅgaṁ tyaktvā) and giving up any desire for the results (phalāni ca). They must be done purely because they are a duty (kartavyānīti). Krishna declares this to be His definite and supreme opinion (niścitaṁ matam uttamam).