Leaving speech for a team member

I have to give a leaving speech for a member of my team who although he has worked for the company for the past three years has only worked for me for four weeks.

I need to say a few words. Any advice?

[Doctor]

Just off the top of my head a good safe way to close would be a line such as "I am sure that [our company's loss] will be [new company]'s gain"

This happened to me once, I mailed round a few people in the dept and asked for anything funny about him, got a few comments and just read them out, worked a treat!