Sunan Ibn Majah — Chapters on Shares of Inheritance — Hadith No: 2749
Translation
It was narrated from ‘Abdullah bin ‘Umar that the Messenger of Allah (ﷺ) said:“Whatever division of inheritance was made during the Ignorance period, stands according to the division of the Ignorance period, and whatever division of inheritance was made during Islam, it stands according to the division of Islam.”