Sayyiduna Anas (may Allah be pleased with him) narrates: A man submitted: O Messenger of Allah (peace and blessings be upon him)! How many prayers has Allah made obligatory upon His servants? The Prophet (peace and blessings be upon him) said: Five prayers. He asked: Is there anything before or after them as well? The Prophet (peace and blessings be upon him) said: Allah has made five prayers obligatory upon His servants. The narrator says: That man swore by the name of Allah that he would neither add to them nor decrease from them. The Prophet (peace and blessings be upon him) said: If he has spoken the truth, he will enter Paradise.
Hadith Referenceصحیح ابن حبان / كتاب الصلاة / 2416
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - «الإرواء» (2/ 4).فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده على شرط مسلم