Would the Messenger of Allah (peace be upon him) advise saving some money or investing all of it in purchasing an apartment, taking into consideration that the available amount is not sufficient to buy an apartment in a safe area?

Borrowing is permissible for the borrower, and an act of devotion for the lender, especially if the borrower intends to repay the debt and has the means to do so. It is preferable to avoid borrowing unless there is an urgent need. Housing can be purchased with available funds or through permissible borrowing, with the caveat that depositing money is not allowed except in Islamic banks.