Deuteronomy 2:6
"Ye shall buy meat of them for money, that ye may eat; and ye shall also buy water of them for money, that ye may drink."
Cross References (ranked by relevance)
Romans 12:17
Recompense to no man evil for evil. Provide things honest in the sight of all men.
Matthew 7:12
Therefore all things whatsoever ye would that men should do to you, do ye even so to them: for this is the law and the prophets.
Numbers 20:19
And the children of Israel said unto him, We will go by the high way: and if I and my cattle drink of thy water, then I will pay for it: I will only, without doing anything else, go through on my feet.