They i.e 'Ali and al-'Abbas (Allah be pleased with them), were quarrelling about what Allah bestowed on His Messenger of Allah (ﷺ), that is, the property of Banu al-Nadir.

Abu Dawud said: He ('Umar) intended that the name of division should not apply to it.
Sunan Abi Dawud Book 20, Hadith 37