How much damage is done by redlining a 2007 bmw 323i?

today i let my friend test drive my 2007 bmw 323i. we went down a long stretch and he was going very fast. i looked over and saw the car was just entering the redline, pretty much half way in the redline and so i made him get out quick..it probably lasted just a few secs. but now im very paranoid and hope this did not damage my engine or car at all....can anyone shed some light on this situation ?