Hanafi
The sources give no view for it here.
الاستثناء في اليمين
هل يجب الاستثناء في اليمين؟
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
Why they differ
In Ibn Rushd’s wordsوَسَبَبُ الْخِلَافِ: مَا قُلْنَاهُ مِنْ أَنَّ الِاسْتِثْنَاءَ هَلْ هُوَ حَالٌّ أَوْ مَانِعٌ؟
The texts
مسألة: الاستثناء في اليمين غير واجب، خلافا لقوم؛ لأنه يحل اليمين كالكفارة، ولأنه لو كان واجبا لم يجز لأحد أن يعقد يمينا، وذلك خلاف الإجماع.
«الإشراف», al-Qadi Abd al-Wahhab p. 885
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.