The Fiqh of Fasting
The Arabic words siyâm and sawm literally mean ‘abstention’ and as such any avoidance even of speech may be called sawm. An example of this comes in sûrah Maryam, verse 26: “I have taken an oath to perform sawm… and as such I will not speak to any human today.” Legally however it means: “for a specific person [the mukallaf who intends it] to abstain from specific matters [the three nullifiers] for a specific period [from true dawn until sundown].”