Cross somebody’s palm with silver
Definition 1 of 1
Pro Tip 1/3Often Metaphorical
This phrase is frequently used in a non-literal sense to imply a bribe or exchange for secrets. 
To get the inside scoop, I had to cross his palm with silver.
Pro Tip 2/3Historical Roots
The phrase originates from older times when silver coins were common currency. 
In historical novels, you'll often find characters crossing palms with silver.
Pro Tip 3/3Archaic Connotation
The idiom is considered old-fashioned and can lend a period feel to the language. 
He crossed the mystic's palm with silver, as was done in ancient tales.