Sahih al-bukhari:6976 Chapter: Avoiding the use of tricks Book 90, Hadith 23

Narrated Jabir bin `Abdullah: The Prophet (ﷺ) has decreed that preemption is valid in all cases where the real estate concerned has not
been divided, but if the boundaries are established and the ways are made, then there is no preemption.
A man said, “Preemption is only for the neighbor,” and then he makes invalid what he has confirmed.
He said, “If someone wants to buy a house and being afraid that the neighbor (of the house) may buy
it through preemption, he buys one share out of one hundred shares of the house and then buys the rest
of the house, then the neighbor can only have the right of preemption for the first share but not for the
rest of the house; and the buyer may play such a trick in this case.”