The answers here are correct, but let me throw something in. You'll need to do a Personal Property Bill of Sale, write down the items included, and make sure to have the prices at $0. If necessary, roll the price of the furniture into the price of the house, if you haven't submitted that contract already. The reasons for this are multiple. One, and it's not a tax issue on your end, since you don't need to worry about that unless you're actually making money on your furniture above and beyond what you originally paid for it, but it is a loan issue. It can affect the terms and down payment amount of the loan. Also, it just muddies the waters, so it's generally easier to keep it simple and let the furniture go for free.
Of course, if the contract is already done and submitted, and the buyer is paying cash for the furniture, then it's really not that difficult, just do the contract and call it a day, just don't submit it with the other paperwork. It's technically none of their business. And again, unless you're actually making money off the furniture, no tax implications.
Just to cover my butt on this, check with an accountant, but I'm pretty sure I'm right on the tax part....