Al Qadi Abi Shuja’ stated there are 4 prerequisite ( شرط ) for Saum.
- A Muslim
- Attain puberty ( baligh )
- Rational ( ‘aql )
- Capable to fast
Imam Ibnu Daqiq elaborated further that when it is stated Muslim, so non-Muslim are not wajib upon them to fast.It is also not wajib for children and crazy people ( lunatic ). As for women, they must be clean from haid.