Money?

A friend asked me to give him a hand. To buy a notebook. At total it is nearly RM4000. At first i agreed to help him without hesitation but after that i felt something wrong. Where did i get that big amount of money? I asked him to bank in first buy until now he has not done that. I trust him alot so i wish he won't make me losing faith on him. Money could spoil relationship if we don't handle properly. I guess next time i got to list down the requirements clearly so that v can make sure no further arguments later.