Vic, Protect yourself first and foremost. This has to be your number one priority. This person - "friend" - asks you to get him some rock? Oh my god... please look at that... what kind of friend asks you - a wonderful person working on staying clean - to go out and get him a piece of sh!t so that he can destroy his life more? This completely translates to me as someone who is willing to destroy your life for his addiction.
Protect yourself, you don't owe this person anything. Not an explanation, not a reason, not one single breath of your precious clean air. He has to take care of his own stuff... not you.
To thine own self be true.
Suga