A sale agreement typically includes both a purchase price for the property as well as terms and conditions. It sometimes happens that a buyer will make an offer subject to certain terms. (I’ll buy your house, but I want to keep the washer and dryer, etc.)
One possible condition concerns “seller contributions.” (For example, I’ll buy your house if you will pay the first $x of my closing costs.) Lenders will generally accept seller contributions as part of a transaction providing they are written into the sale agreement, fully disclosed and only represent a limited fraction of the sale price. Different loan programs have different contribution caps. Lenders and brokers can provide specific advice.
A seller contribution can be a useful bargaining chip in slow markets. (Buy my house and you can have a credit of $x at closing.) It’s a thought that goes a long way with cash-strapped home buyers.