The share button for a quest that can be shared (top) and a quest that cannot (bottom).
The share button appears in the quest log (default J) at the bottom left. Quests can only be shared between group members. The quest will only be shared with members of the correct level (at or above the quest's req level) and those within 49m of the player sharing the quest. Campaign quests, and quests in a series (other than the first quest), cannot be shared. Quests can also not be shared if they started from an item (like 
<The Lost Axe> [5]) or if the player was given an item when accepting the quest (like <Sap for Leather> [5]).
The share dialog.
Once the share button is clicked, all eligible group members receive a confirmation dialog asking if they wish to accept the shared quest. Clicking Yes accepts the quest and adds it to the player's quest log. If the player already has 40 quests in their log or is below the required level to receive the quest, they won't receive this dialog or be notified of the share attempt.
Chat messages[]
The player that shared the quest will see a confirmation statement in their chat log stating who the quest was shared with and whether the quest sharing succeeded or failed.
Success[]
- "You shared the quest with [Player Name].
- "Quest acquired: [Quest]"
Failure[]
- "You failed to share the quest with [Player Name]."
- "You cannot receive a quest that you are already working on."
No eligibility[]
- "There are no group members to share the quest with."