What is the authenticity of the story of the Companion Umayr ibn Waqsh, who entered Paradise without ever prostrating to Allah a single time?

The Companion is Amr ibn Thabit ibn Waqish, also known as Amr ibn Uqaysh or Al-Usayrim, and he was martyred in the Battle of Uhud. He had abstained from Islam due to his wealth from usury, but on the day of Uhud, Allah cast Islam into his heart. So, he went out to fight after embracing Islam without having prayed. He fought valiantly until he was wounded, and when asked about the reason for his fighting, he replied that it was out of anger for Allah and His Messenger. He died as a martyr, and the Prophet, peace and blessings be upon him, bore witness for him to Paradise, saying: "Indeed, he is among the people of Paradise."