Suppose we have estimated 5 user stories to complete in a sprint and completed all of them with testing, buffer time and for expected bugs.Still we have 2-3 days left for one of the developer. Can we pull a future user story in current sprint knowing that only development or part of development can be completed in current sprint?
Can we pull future user stories in current sprint?
agile;scrum;sprint
Certainly, you should be able to pull in whatever is at the top of the product backlog.But be careful.Make sure that pulling in the new story will not interfere with the delivery of the stories you have actually committed to.  You really should make sure they are wrapped up and ready to go (deployed even).  At the very least you need to make sure that the new probably-unfinished code does not get mixed up with the finished deliverable code.