One of the reasons of crse was to not to forbid from sins

On those who disbelieve from among the children of Isra’il , a curse was pronounced by Dawud and ‘Isa, Son of Maryam. All this because they disobeyed and used to cross the limits.

They used not to forbid one another from Al-Munkar (wrong, evil-doing, sins, polytheism, disbelief) which they committed. Vile indeed was what they used to do.

Al maeda 78-79