مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2033
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Ibn ‘Abbas said: People should reduce it (the bequest) from one third to one quarter [of the estate], because the Messenger of Allah (ﷺ) said: “One third is a lot.”
Musnad Ahmad 2034Its isnad is saheeh, al-Bukhari (2743) and Muslim (1629)]