Historical Rules · 4 February 2011
Rule 903.6
Official source text from the 4 February 2011 Rules release
At the start of the game, each player puts his or her commander face up next to his or her library. The commanders start the game in the command zone. Then each player shuffles the remaining 99 cards of his or her deck so that the cards are in a random order. Those cards become the player’s library.