On this page of the Assassin's Creed Valhalla guide, you will find a detailed walkthrough of a side quest in the Hordafylke region: The Rekindling.
Reward for completing the mission: 1200 XP, chest key.
In the place marked on the image above, you will meet a woman, a raid-loving wife, who needs some additional excitement along with her husband.
Go inside the hut and start destroying the couple's belongings. When it's not enough, equip the torch and set the hay on fire, which will end the mission.