What is the authenticity of the circulated story about Hashim ibn Utbah killing a lion in one of the battles, which includes details such as "the courageous, heroic Muslim man running towards the lion in a terrifying, unimaginable scene" and "he leaped upon it like a lion on its prey, and stabbed it multiple times until he killed it"?

Hashim bin Utbah bin Abi Waqqas was one of the courageous heroes of Islam. He was born during the lifetime of the Prophet (peace be upon him) and witnessed the Battle of Yarmouk, where he lost an eye. He also participated in the conquest of Damascus. He carried the banner of Ali on the Day of Siffin and was killed on that day. He was known for his bravery and daring. Some considered him among the Companions due to his having lived during the time of prophethood.

As for the story of his killing of the lion named "Al-Muqarrit," mentioned in the question, it was narrated by Al-Tabari in his history and by Ibn Kathir. However, the chain of narration for this story is weak, as it was narrated by Sayf ibn Umar al-Tamimi, who is abandoned and accused of heresy, and narrates fabricated reports, and by Shu'ayb ibn Ibrahim al-Kufi, who is unknown (jahalah).