The term Commitment was removed from The Scrum Guide (pdf) and replaced by the term Forecast back in 2011. Here is my rant against the concept of commitment as it is still used by many otherwise agile teams. If you don’t do scrum, but any other development method that ties a fixed set of development tasks to an iteration, then this article is also for you. You must not mistake ceremonial commitment with the commitment of individuals and teams to deliver excellent work. We all agree the latter is a great and desirable thing. In this article I am only talking about the former.
Sprint commitment means, that a team of software developers have to commit to finishing a fixed number of stories in the next iteration. I guess the hope often is, that due to the pressure created by such a commitment more stories are developed per time unit. I also heard the reasoning commitment would improve planability of a development project or that it increases the motivation of developers. I think that is all wrong.