Full Sharh — Riyad as-Salihin 538
وعن سهل بن سعد رضي الله عنه عنه عن النبي صلى الله عليه وسلم قال: "إن في الجنة بابًا يقال له: الريان، يدخل منه الصائمون يوم القيامة لا يدخل منه أحد غيرهم يقال: أين الصائمون؟ فيقومون لا يدخل منه أحد غيرهم، فإذا دخلوا أغلق فلم يدخل منه أحد" ((متفق عليه))
English Translation
Sahl bin Sa'd (May Allah be pleased with him):: The Prophet (ﷺ) 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.".
Source
Riyad as-Salihin(رياض الصالحين)
The Book of Virtues
Hadith Number
538