{That ye study to be quiet} (philotimeisthai h(8873)uchazein).
First infinitive dependent on parakaloumen (verse  10 , we
exhort you), the second on philotimeisthai (old verb from
philotimos, fond of honour, philos, tim(885c)). The notion of
ambition appears in each of the three N.T. examples ( 1Th 4:11  2Co 5:9  Ro 5:20 ), but it is ambition to do good, not evil. The
word ambition is Latin (_ambitio_ from _ambo, ire_), to go on
both sides to accomplish one's aims and often evil). A preacher
devoid of ambition lacks power. There was a restless spirit in
Thessalonica because of the misapprehension of the second coming.
So Paul urges an ambition to be quiet or calm, to lead a quiet
life, including silence ( Ac 11:18 ). {To do your own business}
(prassein ta idia). Present infinitive like the others, to have
the habit of attending to their own affairs (	a idia). This
restless meddlesomeness here condemned Paul alludes to again in
 2Th 3:11  in plainer terms. It is amazing how much wisdom people
have about other people's affairs and so little interest in their
own. {To work with your own hands} (ergazesthai tais chersin
hum(936e)). Instrumental case (chersin). Paul gave a new dignity
to manual labour by precept and example. There were "pious"
idlers in the church in Thessalonica who were promoting trouble.
He had commanded them when with them.