The ruling on purchasing residential apartments before they are completed

Question:
The second questioner says: What is the ruling on purchasing a residential apartment through installment payments, where the buyer understands the reasonable terms, and the seller is responsible for the residential units, knowing that the buyer does not acquire the apartment until the second party fulfills the reasonable terms, and he does not know the full details of its completion regarding the second party’s execution.

Answer:
He should not buy from him unless he knows the apartment and is aware of all its details, and buys it for a price due immediately or a deferred price, whether specified or not. As for the delivery, and the fact that delivery is delayed, there is no harm in that according to the condition, and the timing of delivery is according to the condition agreed upon between the two parties. However, it is not permissible for him to sell it until he has taken full possession of it and knows it completely.