See the colour of somebody’s money
Definition 1 of 1
Pro Tip 1/3Trust Issues
Used when you doubt someone's ability to pay and want assurance before providing goods or services. 
Before I hand over this artwork, I need to see the colour of your money.
Pro Tip 2/3Before Action
This phrase often implies payment or proof of funds is required before action is taken. 
The decorator said he wouldn't start painting until he'd seen the colour of our money.
Pro Tip 3/3Informal Context
It's casual and mainly used in informal conversations, not formal agreements or legal terms. 
Mate, I'll need to see the colour of your money before I agree to that bet.