Fasting on Saturday in non-obligatory - a study of Hadith
Allaah has enjoined us to fast the month of Ramadaan and impose it upon us, saying: "O ye who believe! The fasting is prescribed for you, as He has written on those before you, that ye may be careful." (Last verses (183-185)).
In the words of the Almighty (may you be careful) a reference to the virtue of fasting at all, because it is a reason to achieve piety.
This is the year in which it is narrated that it is permissible to fast for many days of the year, such as fasting six days of Shawwaal