The rookie transition program is a four-day event in which rookies go through an 'orientation' program. Basically it's a program used to tell these young kids how to keep out of trouble and how to manage their money.
The rule Muhammad broke was bringing a female to his hotel room. It happened just hours after the rookies were given the rules, one of which included: no guests in the rooms.
The Timberwolves organization confirmed that Shabazz had been sent home from the program early and Flip Saunders said this in a statement, "We have been made aware of the circumstances surrounding Shabazz Muhammad's dismissal from the NBA's Rookie Transition Program in New Jersey. The team fully supports the NBA's rules and policies in all matters pertaining to this situation and we will abide by the league's action."
This isn't the first incident during the Rookie Transition Program. In 2008, Mario Chalmers, Darrell Arthur and Michael Beasley had a party in their hotel room and there were women and marijuana in the room. Chalmers & Arthur were both fined $20,000 while Beasley was fined $50,000.
Muhammad will make roughly $1.8million this season, that's of course before the League imposes a fine.