[Machine] The Messenger of Allah ﷺ said, "Whoever buys a slave without specifying his price, then he has nothing (i.e. no rights) over him."  

قَالَ رَسُولُ اللَّهِ ﷺ «مَنِ اشْتَرَى عَبْدًا وَلَمْ يَشْتَرِطْ مَالَهُ فَلَا شَيْءَ لَهُ»