Chapter IV Sloka 15

@v< }aTva kt< kmR pUvERrip mumu]ui->,
k kmERv tSmav< pUvER> pUvRtr< ktm!

eva jtv kta karma 
prvairapi mumukubhi |
kuru karmaiva tasmttva 
prvai prvatara ktam ( 4|15)||

Having known, this, the ancient seekers after freedom also performed action; therefore do thou also perform action, as did the ancients in days of yore.
Knowing thus that the Self can have no desire for the fruits of actions and cannot be tainted by them, and knowing that no one can be tainted if he works without egoism, attachment and expectation of fruits, do thou perform your duty.
If your heart is impure, perform actions for its purification. It you have attained Atma-Jnana or the knowledge of the Self, work for the well-being of the world. The ancients such as Janaka and others performed actions in the days of yore. So do thou also perform action.