Muwatta Imam Malik (Riwayat Ibn al-Qasim)

And with this same chain (it is narrated from Sayyiduna Abu Hurairah, may Allah be pleased with him) that the Messenger of Allah, peace and blessings be upon him, said: "We are the last to come, but on the Day of Resurrection we will be the foremost, even though the Book was given to them (the Jews and Christians) before us and was given to us after them. So this day became obligatory upon them, but they differed regarding it, then Allah guided us to it, therefore all people are behind us. The day of the Jews is tomorrow (Saturday) and the day of the Christians is the day after tomorrow (Sunday)."