What is the interpretation of the noble verse: "Among the believers are men who have been true to their covenant with Allah – some of them have fulfilled their vow, and some are still waiting"?

Ibn Kathir said in his Tafsir (exegesis) of the verse: {Among the believers are men who have been true to their covenant with Allah. Some of them have fulfilled their vow [by martyrdom], and some are still waiting, and they have not changed [their commitment] in the least.} [Al-Ahzab: 23] that this verse was revealed concerning Anas ibn Al-Nadr, may Allah be pleased with him. Ibn Kathir mentioned the hadith of Anas ibn Malik that his uncle, Anas ibn Al-Nadr, did not witness the Battle of Badr, and he grieved over it and swore that he would certainly witness another battle with the Messenger of Allah, peace and blessings be upon him. Then he witnessed the Battle of Uhud and fought fiercely until he was martyred. Eighty-some blows, stabs, and arrow wounds were found on his body, and his sister recognized him only by his fingertips. So this verse was revealed concerning him and his companions. Ibn Ashour mentioned in "Al-Tahrir wa Al-Tanwir" that the verse was revealed concerning men among the believers who stood firm against the enemy on the Day of Uhud, including: Uthman ibn Affan, Anas ibn Al-Nadr, Talhah ibn Ubaydillah, Hamza, Said ibn Zayd, and Mus'ab ibn Umayr. Some of them were martyred, and some fought and survived. The meaning of "have been true to their covenant with Allah" is that they fulfilled what they covenanted.