“Any slave who has made a contract to buy his freedom for one hundread Uqiyyah and pays it all except ten Uqiyyah; he is still a slave.” (One Uqiyyah is equal to 40 Dirham.) (Using translation from Ibn Mājah 2519)
قَالَ رَسُولُ اللهِ ﷺ «أَيُّمَا عَبْدٍ كُوتِبَ عَلَى مِائَةِ وُقِيَّةٍ فَأَدَّاهَا إِلَّا عَشْرَ أَوَاقٍ ثُمَّ عَجَزَ فَهُوَ رَقِيقٌ»