Sunan Ibn Majah
2485
Sahih+3

It was narrated from Ibn `Abbas that the Messenger of Allah (ﷺ) said:“Every division that was allocated according to (the rules of) the Ignorance days, stands as it is, and every division that was allocated according to (the rules of) Islam, stands according to the rules of Islam.”

SahihAl-Albani
SahihMuhammad Fouad Abd al-Baqi