Is what the Shia claim true, that Umar ibn al-Khattab (may Allah be pleased with him) used to flee from the Jews and escape from battles, and what are the names of the battles he participated in and who did he kill?

Umar ibn al-Khattab, may Allah be pleased with him, witnessed all of the Messenger of Allah's, peace and blessings be upon him, battles and did not miss any of them. He played a significant role in fighting the disbelievers. What confirms this is his killing of his maternal uncle, Al-As ibn Hisham, in the Battle of Badr. The claim by the Shia that he fled from battles is false, for his bravery, courage, and severity against the disbelievers have been affirmed by continuous transmission (tawatur), and his awe-inspiring presence was well-known among the polytheists. Furthermore, Umar, may Allah be pleased with him, was keen on fighting Quraish during the Treaty of Hudaybiyyah. As for the narratives of Khaybar and Hunayn, which the Shia use to impugn his courage, they do not indicate his flight, but rather his firm and unwavering stance. In Khaybar, Umar returned because victory had not yet been achieved, not out of fear, even though the Jews were inside their fortresses. The noble verse (إِلَّا مُتَحَرِّفًا لِقِتَالٍ أَوْ مُتَحَيِّزًا إِلَى فِئَةٍ) "unless maneuvering for battle or joining a company" permits such a tactical retreat. And in Hunayn, Abu Qatadah's narration did not indicate Umar's flight; rather, other narrations point to his steadfastness with the Prophet, peace and blessings be upon him.