Hanafi
The sources give no view for it here.
بيع العبد الآبق
هل يجوز بيع العبد الآبق؟
Each school’s answer
In our wordsHanafi
Not stated in the sources
Maliki
Not stated in the sources
Shafi'i
Not stated in the sources
Hanbali
Not stated in the sources
The texts
مسألة: بيع الآبق غير جائز خلافا لقوم؛ لأنه غرر لا يدري هل هو سالم أم تالف؟ وهل هو على صفته أو قد تغيرت؟ ولأنه لا يقدر على تسليمه.
«الإشراف», al-Qadi Abd al-Wahhab p. 563
From the schools’ own books
Maliki
The sources give no view for it here.
Shafi'i
The sources give no view for it here.
Hanbali
The sources give no view for it here.
What is «in our words» is our standard wording; the books’ texts stay as they are.