Facebook's Friendships page displays information regarding your friendships with other people on Facebook, including timeline posts, photos, shared likes and mutual friends. Your friendship with up to two people can be displayed at any given time on the Friendship page, including a complete list of mutual friends between the three of you. Accessing this view of your friendships requires that you visit the profile of at least one friend to get the ball rolling.
Enter the name of one of your friends in the search bar in the Facebook header and select her from the list. It doesn't matter which of your two friends you search for first, as the two-person look-up tool requires you to enter both names.
Click the ... button below your friend's cover photo and select See Friendship to load the Friendship page, which is the only place you can look up two friends at once.
Click the More button on the Friendship page, type in the names of the two friends whose mutual friends you want to view, and select the appropriate person when Facebook suggests him. Click See Friendship once both friends are selected to view a Friendship page regarding both friends.
Click Mutual under the Friends heading to show a complete list of friends the three of you share.