Fathwa - The sale of this land is valid

Question
We bought a piece of residential land about 25 years ago.The land has
Railway crossing near it.We have sold the land to third person an
received some amount inadvance from him,when remaining amount will be
paid the ownership will be transfered to purchaser.After we have
received the amount of advance we come to know that the railway line
results in some cracks in nearby houses. We have not told purchaser
about this as we were unaware of the fact...No what we shoul ddo? will
this sale transaction be valid?
Answer
All perfect praise be to Allaah, The Lord of the Worlds. I testify
that there is none worthy of worship except Allaah, and that Muhammad,
is His Slave and Messenger.
What you have mentioned does not affect the validity of the sale and
you are not obligated to tell the buyer about it because if the
railway existed during the sale, then it is something that cannot be
hidden, and if it did not exist, then the occurrence of what you
mentioned )i.e. the cracks in nearby houses( is just an expectation
that does not count at all.Again, you have sold the land to him and he
may benefit from it by building or in other purposes.
In any case, expecting an effect to occur due to therailway line that
is near the land does not affect the stated sale and it is not
obligatory to tell the buyer about it.
Allaah Knows best.