A better question might be, "Which is more important in sales - commitment or motivation?"

Let's discuss the difference first.

Commitment is the willingness to do whatever is required to succeed in sales, at reaching quota, achieving goals and closing a particular deal or account.  Whatever it takes (ethically).  It's not, whatever it takes "as long as I'm comfortable" or "as long as it's not too difficult" or "as long as it's not too scary".  Unconditional commitment.  The more difficult the challenge, the stronger the resolve must be.  How many of your salespeople have that kind of commitment?  Do you really know or just think you know?  That's one of the important findings we measure at Objective Management Group.  Not general commitment for success in life as measured in nearly every other assessment; commitment to succeed at selling!

Motivation is the incentive to do what is required in sales.  It is why someone will show up, day after day, for this difficult, sometimes demotivating, always humbling challenge.  Whether it is the rewards, recognition, money, satisfaction, revenge, things, or mastery, what is it that's powerful enough to make people thoroughly emmerse themselves in selling each day.  Sales Motivation is another one of the important findings we measure.  Not vanilla motivation or drive as measured in nearly every other assessment; the motivation to sell!

Now that you understand the difference between Commitment and Motivation, which is more important?  Can you have one without the other?  Let's investigate.

When a salesperson is motivated but lacking commitment we have the carrot but no stick.  The salesperson has reason but without resolve.  A dreamer who will become discouraged.

When a salesperson is committed but lacking motivation we have the stick, but no carrot.  A machine that will break down and lose effectiveness over time.

It should be obvious that we need both - sales specific commitment and motivation - along with Desire - How badly the individual wants to succeed in sales. (Yes, we measure that too!)

While selling skills and supporting strengths are an important part of the success equation, nothing is more important than Commitment, Desire and Motivation.  (Here's one more article on Desire and one more on  Motivation.)