'Duty' in the Bible

Now we command you, believers, in the name of our Lord Jesus Christ and by His authority, that you withdraw and keep away from every brother or sister who leads an undisciplined life and does not live in accordance with the tradition and teaching that you have received from us.

For you yourselves know how you ought to follow our example, because we did not act in an undisciplined or inappropriate manner when we were with you [we were never idle or lazy, nor did we avoid our duties],

Indeed, we hear that some among you are leading an undisciplined and inappropriate life, doing no work at all, but acting like busybodies [meddling in other people’s business].