Historical Rules · 29 September 2017
Rule 115.2a
Official source text from the 29 September 2017 Rules release
Playing a land is a special action. To play a land, a player puts that land onto the battlefield from the zone it was in (usually that player’s hand). By default, a player can take this action only once during each of his or her turns. A player can take this action any time he or she has priority and the stack is empty during a main phase of his or her turn. See rule 305, “Lands.”