Sahl bin Sa`d (Radhiallaho anha): The Prophet (Sallallaahu ‘alaihi wasallam) said,
“In Jannah there is a gate which is called Ar-Raiyan through which only those who observe Saum (fasting) will enter on the Day of Resurrection. None else will enter through it. It will be called out, “Where are those who observe fasting?” So they will stand up and proceed towards it. When the last of them will have entered, the gate will be closed and then no one will enter through that gate.”
This Hadith tells us about the special distinction of those who observe Saum. “Only those who observe Saum” signify the faithful who not only observe Saum during the month of Ramadan but also frequently observe voluntary fasts over and above the obligatory ones, otherwise Saum of Ramadan are compulsory for every Muslim.