When you rent an apartment check carefuly if the apt is the property of the one who is renting it to you

It happenned to Marc and a friend of his, I showed them a nice apt at a very reasonable price, because of a small detail, I realized that the apartment might not be the property of this guy who was trying to rent it.
I checked thoroughly and it happended that the apt belongs to his mother in law who was living in Tiberias with a son of hers and who didn't want to rent it at all, as well as her son there.

I asked immediately the 2 renters not to sign; instead of being thankful, they were very upset with me, they keep refusing to answer my phone calls; I didn't understand; ok,my english is not so good, I thought they might not have understood the illegal side of what they were ready to participate but today I tell them that I never offer the apartment to anybody else and will never, I tell them that they did the right thing, and for sure I did the right thing. I wish them to find the right apartment for them and the best for their life. Avraham