701.16a

To reveal a card, show that card to all players for a brief time. If an effect causes a card to be revealed, it remains revealed for as long as necessary to complete the parts of the effect that card is relevant to. If the cost to cast a spell or activate an ability includes revealing a card, or if a card is revealed because an ability is activated from a hidden zone (see rule 602.2a), the card remains revealed from the time the spell or ability is announced until the time it leaves the stack. If revealing a card causes a triggered ability to trigger, the card remains revealed until that triggered ability leaves the stack. If that ability isn’t put onto the stack the next time a player would receive priority, the card ceases to be revealed.