Chapter III Sloka 35

ïeyaNSvxmaeR ivgu[> prxmaRTSvnuiótat!,
SvxmeR inxn< ïey> prxmaeR -yavh>.

ŝrey˜nsvadharmo viguġa×
paradharm˜tsvanu˙÷hit˜t | 
svadharme nidhanaĠ ŝreya× 
paradharmo bhay˜vaha× ( 3|35)||

Better one's own dharma (calling, duty) though devoid of merit
than the dharma of another, though well done perfectly.
Better is death in one's own dharma than in another's;
the duty of another is fraught with fear (is productive of positive danger).

SwamiChinmayananda 's comments:

Swadharma is not the caste duties which accrue to an individual due to the sheer accident of birth. In its right import here, it should be only the type of Vasanas that one discovers in oneself in one's own mind. To act according to one's own taste, inborn and natural, is the only known method of living in peace and joy, in success and satisfaction. To act against the grain of one's own Vasanas would be acting in terms of Para-dharma; and how much this is fraught with fear, is very well known.