With so much emphasis placed on Getting to Yes, we often forget the power - indeed the necessity -- of saying "no."

Think of yourself in that iconic bargaining environment, the foreign bazaar.  No matter how much of a buyers' market you're in, at some point, the seller must say no -- otherwise you'd just bargain him down to zero, or perhaps negotiate a deal in which he pays you to take the merchandise off his hands.  Fortunately for negotiators everyone, the Getting to Yes guy -- William Ury -- has also written an entire book on The Power of a Positive No.  As Time Magazine wrote at the time of "No's" release,

In The Power of a Positive No, Ury offers guidance on the flip side of reaching an agreement: how to deal with a situation in which you simply want to put your foot down. No is so often hard to say, Ury writes, because it highlights the "tension between exercising your power and tending to your relationship"--in other words, between getting what you want in the short term and keeping everyone happy for interactions down the road. People often err in one direction or the other, prioritizing either the relationship by saying yes when they long to say no or their own power by brusquely saying no and alienating the person they're dealing with. Then there is the ever popular route of avoidance--saying nothing at all and gaining neither what you want nor goodwill.

See Why Almost Everyone Has Trouble Saying No.

Ury's answer to "no" avoidance?

[S]erve your no sandwiched between two yeses. It will go down more easily and preserve your relationship yet still allow you to take a stand.

How does the famous "getting to yes" guy say "no"?  By "focusing on underlying interests instead of positions (discussing what you want instead of the way you've decided to get there) [and] developing another option ( . . . Plan B)."  To accomplish this goal, the negotiator must ask diagnostic questions about his bargaining partner's needs, fears, preferences and priorities.(.pdf of Northwestern Professor Leigh Thompson's enduringly great article Why Negotiation is the Most Popular Business School Course; see also chapter one of her must-read The Mind and Heart of the Negotiator here).

Assume, for instance, that you're selling software and your customer wants a broad indemnity agreement that amounts to a virtual insurance policy.  You know the type.  "I want to be indemnified for all litigation arising from my company's use of your software.  It's non-negotiable.  We'll pull out of the deal if you don't provide it to us."

Before saying "no, no, no" or feeling the need to temporize or mumble something unintelligible, determine whether your customer's demand is primarily being driven by need, desire, or fear.  Here, the underlying interest is perceived need based upon fear of potential liability.  Rest assured that your customer is not worried about everything.  There's some particular danger lurking in the back of his mine or in the contemplation of the manager to whom he's reporting. 

The diagnostic question is simple:  "what type of potential liabilities are you worried about?" When your customer answers your question, the "yeses" your "no" can be sandwiched between are legion.   

"We're always happy to craft an indemnity agreement that covers potential liabilities arising from, i.e., defects in the software that cause the type of harm you're worried about.  In fact, because infallible software has yet to be developed, we like to offer our customers a suite of services to quickly remedy any "defects" to prevent the liabilities you're concerned with.  And now that we're talking about it, let's define "defects" so that it fully expresses both of our understandings going forward.

The key is to slow yourself down during the negotiation so that you have time to reframe your "no" as an opportunity for both parties to get more of what they really want than they fear they need. 

As a former pastor of mine once told me, "God never says 'no' to a prayer.  S/he says 'yes,' 'later' or 'I have something better in store for you.'  Approach the material world in the same manner as he does and not only your opportunities, but your heart, will grow in the practice.