...In response to his letter...in which he writes about the situation of his health and also that he suffers from hostile neighbors.
Regarding his health, he needs to consult with two expert doctors and to do as they instruct, and the Torah gave permission (which also means power) to the doctor to heal.
Regarding what he writes about bad neighbors, usually this comes from lack of Kavanah (intent, concentration) in the morning blessings when we pray, “that You will save us...and from a bad neighbor,” and mainly when we don’t put effort properly regarding the bad neighbor that is in the person’s heart, which is the evil inclination. Automatically, when we add in both matters, G-d reciprocates measure for measure, but many times more, and we see an improvement also regarding the literal bad neighbor. It would also be correct to check the Mezuzos in his home, that all of them should be Kosher, and also his Tefillin...
(From a letter of the Lubavitcher Rebbe King Moshiach Shlita, Igros Kodesh vol. 8, pg. 207-208)
