In this section

Historical Rules · 1 April 2011

Rule 101.2

Official source text from the 1 April 2011 Rules release

When a rule or effect allows or directs something to happen, and another effect states that it can't happen, the "can't" effect takes precedence. Example: If one effect reads "You may play an additional land this turn" and another reads "You can't play land cards this turn," the effect that precludes you from playing lands wins.

Find this number in the current Rules