In this rule

Historical Rules · 3 May 2019

Rule 120.3a

Official source text from the 3 May 2019 Rules release

Permalink

The same principles apply if the player who’s making the choice is not the player who would draw the card. If the latter player has no cards in their library, the choice can be taken. If an effect says that the latter player can’t draw a card, the choice can’t be taken.

Find this number in the current Rules