Whoever come closest - you've been warned
But niggas don't get the picture 'til the weapons is drawn

from R. Kelly (Ft. Jay Z) – Fiesta (Remix) Lyrics on Rap Genius

Meaning

He’s warning his enemies and telling them not to get up in his face, but gangstas always think he’s playing and don’t wanna listen until it’s too late and someone’s pointing a gun at them.

This is also a play on double meaning of draw:
1) “draw” as in “paint” (hence the usage of the word “picture”)
2) “draw” as a slang for pulling out a gun

To help improve the meaning of these lyrics, visit “Fiesta (Remix)” by R. Kelly (Ft. Jay Z) Lyrics and leave a comment on the lyrics box