Musnad Ahmad 30:3512

Rawh narrated to us, Sa’id and ‘Abd al-Wahhab narrated to us, from Sa’id, from Qatadah, from ‘Abd al-Rahman ibn Adam, from Abu Hurayrah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, Allah, the Almighty and Majestic, prescribed Friday for those who were before us, but the people differed regarding it. Then Allah guided us to it, so the people are followers to us regarding it. So today is for us, and for the Jews is tomorrow, and for the Christians is the day after tomorrow: for the Jews is the day of Saturday, and for the Christians is the day of Sunday."