Bhagavad Gita Verse 14, Chapter 4

na maam karmaani limpanti na ma karmaphale spruhaa |
iti maam yo bhijaanaati karmabhirna sa badhyate || 14 ||
 
Actions do not stain me, nor do I covet fruits of action. One who knows me in this manner is never bound by actions.
 
na : do not
maam : me
karmaani : action
limpanti : stain
na : not
ma : I
karmaphale : fruits of action
spruhaa : covet
iti : in this manner
maam : me
yaha : one who
abhijaanaati : knows in essence
karmabhih : with actions
na : not
sah : he
badhyate : bound
 
So far, Shri Krishna clarified and elaborated upon key topics within karmayoga. First he gave the paramparaa or tradition of the teaching. He then revealed his nature as Ishvaraa, and explained the method by which he manifests as an avataara. Finally, he explained how he responds in the exact manner that one approaches him.
 
As we get further into karmayoga, we slowly begin to lost our attachment to the fruits of our action, which is the first stage in karmayoga. In this chapter, Shri Krishna urges us to move to the next stage in this journey where we begin to lose the notion of doership.To highlight this point, Shri Krishna says that as Ishvaraa, even he knows that actions are happening in prakriti, and therefore he is not the doer of those actions, but he is beyond all action. He puts this poetically by saying that actions do not "stain" him.
 
Why is Ishvara beyond all action? At its core, any action happens when there is an imbalance or vacuum. Wind travels from high pressure areas to low pressure areas. Electric current moves when there is a difference in voltage. The mind creates a thought because of our vaasanaas. But Ishvara is all-complete and self-sufficient. Therefore, he does not need to act. He is only a witness.
 
If there is a reflection of the sun in a pond, and if dirt is thrown on the pond, the sun is not stained by that dirt. Similarly, since actions are performed by prakriti, there is no impact to Ishvaraa. In this and other shlokas of this chapter, Shri Krishna reminds us that just like he knows that he is not the doer or enjoyer of actions, so should we have the exact same conviction.