Genesis 40:14 - It's a two-way street.

But think on me when it shall be well with thee, and shew kindness, I pray thee, unto me, and make mention of me unto Pharaoh, and bring me out of this house:

There is a marked resemblance between Joseph's request in consideration for his kindness and that of Rahab's. They both asked for help to be rescued and did not expect to be paid for their services. Their expectation was an act of kindness for a act of kindness in return (Joshua 2:12). I scratch your back; you scratch my back.