Hadith

"That person, whose neighbour is not safe from his evils, will not enter Jannah." (Bukhari / Muslim)

Explanation:

Jannah depicts absolute good fortune and eternal salvation. According to this Hadith, when a person ruins the life of his neighbour by his evils, he does not deserve this good fortune.

A person must sacrifice something in order to get something. It is truly a "bad deal" to sacrifice the eternal salvation by harming the neighbour. While one could have got this salvation by not even doing anything.

[English version of "Aadaab voisin" – Al Jamiat – Vol.3 No.8]