'Umar bin Sa'ad bin Abi Waqqas

https://www.wikiwand.com/en/Sa%27d_ibn_Abi_Waqqas

Umar ibn Sa'ad (Arabic: عمر بن سعد‎) (fl. 620–686) was the son of Sa'ad ibn Abi Waqqas. He was a clergyman, and took orders from Ibn Ziyad. He led the troops that murdered Husayn ibn Ali in the Battle of Karbala. He was killed by Al-Mukhtar's army. The historian Tabari has quoted Umar ibn Saad to have said to Ubaydullah ibn Ziyad, "By God, the sincerity I performed towards you with regard to killing Husayn was such that if I had performed such sincerity for my father, I would have fulfilled his rights. He also had a son Hafs Bin Umar ibn Saad bin Abi Waqqas who was according to history killed by his own mother in the government of Al-Mukhtar."