Sahih al-Bukhari 2463

Neighbors have rights that must be fulfilled. The Prophet (may Allah's peace and blessings be upon him) encouraged Muslims to maintain good relations with their neighbors.

In this respect, he said that Jibrīl kept reminding him of the neighbor's right until he thought that the neighbor would be assigned a share of the inheritance, due to the significance of the neighbor's right and his entitlement to kind treatment. Hence, there should be a good and healthy relationship between neighbors where the rights of neighborhood are observed and harmful words and acts are avoided.

A sign of being kind to one's neighbor and of observing his rights is to be willing to benefit him in a way that does not inflict much harm on oneself. For example, when a neighbor wishes, for his own convenience, to fix a wooden bar into the wall of his neighbor, the latter should allow him to do so on two conditions: there is a need for that; and there is no negative impact on him.

The ruler may even force one to allow his neighbor's insertion of wood into his wall. If the owner of the wall is harmed or there is no need for the insertion of wood, then a negative impact should not be eliminated by something similar. The principle is that no harm is to be inflicted on a Muslim. Since Abu Hurayrah (may Allah be pleased with him) recognized the wise purpose of that confirmed act of Sunnah, he condemned people for not acting on it.

He even threatened to force them to act upon it in fulfillment of the rights of neighbors which Allah, the Almighty, has enjoined. Finally, Muslim scholars have unanimously agreed on forbidding the insertion of wood into the neighbor’s wall, if this would harm the neighbor, except with his permission. Indeed, the Prophet (may Allah's peace and blessings be upon him) said: “There should be neither harm nor malice.”