On this page of the Assassin's Creed Valhalla guide, you will find a detailed walkthrough description of the side quest Permission to Weep.
Rewards: 1,200 XP.
In the place marked in the image above, you will meet a Viking who laments that all his crewmates have died and his family has been taken by the plague.
Unfortunately, the man cannot lament and mourn the dead, so he asks you, a Viking, for permission. If you have level 3 charisma you can give him your blessing and complete this quest. Fighting this opponent will only unleash his wrath while not passing the mission.