Illegal Lending Practices?

I need some help from my fellow agents. I know there are regulations preventing builders from offering incentives to buyers for using their lender versus another lender but what about bank owned properties? Is there any law or regulation that addresses this issue?

An example: Lender ABC forecloses on a property and then puts it up for sale. My buyer looks at the property and decides to make an offer. ABC sends me the addendum and it it clearly states that if my buyer uses ABC as their lender then ABC will pay 3% in closing costs and also offer a home warranty. If my client uses another lender then ABC will not pay for a warranty and will pay zero closing costs (no exceptions).

I am pretty sure this is not legal but I do not know where to locate the information to back up my assumptions. I also may be wrong. The new regulations may only apply to new home builders. If anybody can clear this up for me or point me in the right direction I would appreciate it.