Sahih Muslim
The Book of Prayers (Kitab Al-Salat)
Book Number: 004 / Hadith Number: 1861
Abu Huraira reported Muhammad, the Messenger of Allah (may peace be upon him), as saying: We who are the last would be the first on the Day of Resurrection but they (other Ummahs) were given the Book before us and we were given after them, and this was the day that was prescribed for them but they disagreed on it. And Allah guided us to it. and they came after us with regard to it, the Jews observing the next day and the Christians the day following that.