If I smoke, how long will it take me to pass a test?

Ok so i haven't smoked for over a month, and i want to stay clean for a while so i can get a job, my friend wants to smoke me out just once, so if i havent smoked in about 5 weeks then i smoke just once, how long will it take for me to pass a piss test? he says only 3 or 4 days

hes lyin 2 u takes 30 dayz or so not unless u use detox product