Hadith for the day

I can see years of doctrinal discussion over this one.? No one (let’s say Person A) should prevent his (Person A’s) neighbour (Person B) from fixing a wooden peg in HIS wall.? Is “HIS” Person A or Person B?

Is it a shared wall between two properties?

Does the design and placement of said peg need to be agreed first?

These are critical issues.