if you are and wish to become and remain a long-term employee at your organization, i agree with Nishnabotna. do the job - it will affect your future.

it is not an easy pill to swallow - but nothing is forever.

you may become great friends. and maybe that person could even become your supervisor. what memory do you want them to have of you?

besides, if it doesn't go well, maybe later you can slip 'em a banana peel.

do document - everything.