Hadith: Verily, I shall give this banner to a man who loves Allah and His Messenger, and Allah will grant victory at his hands."

عَنْ أَبِي هُرَيْرَةَ رضي الله عنه أَنَّ رَسُولَ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ قَالَ يَوْمَ خَيْبَرَ:
«لَأُعْطِيَنَّ هَذِهِ الرَّايَةَ رَجُلًا يُحِبُّ اللهَ وَرَسُولَهُ، يَفْتَحُ اللهُ عَلَى يَدَيْهِ» قَالَ عُمَرُ بْنُ الْخَطَّابِ: مَا أَحْبَبْتُ الْإِمَارَةَ إِلَّا يَوْمَئِذٍ، قَالَ فَتَسَاوَرْتُ لَهَا رَجَاءَ أَنْ أُدْعَى لَهَا، قَالَ فَدَعَا رَسُولُ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ عَلِيَّ بْنَ أَبِي طَالِبٍ، فَأَعْطَاهُ إِيَّاهَا، وَقَالَ: «امْشِ، وَلَا تَلْتَفِتْ، حَتَّى يَفْتَحَ اللهُ عَلَيْكَ» قَالَ فَسَارَ عَلِيٌّ شَيْئًا ثُمَّ وَقَفَ وَلَمْ يَلْتَفِتْ، فَصَرَخَ: يَا رَسُولَ اللهِ، عَلَى مَاذَا أُقَاتِلُ النَّاسَ؟ قَالَ: «قَاتِلْهُمْ حَتَّى يَشْهَدُوا أَنْ لَا إِلَهَ إِلَّا اللهُ وَأَنَّ مُحَمَّدًا رَسُولُ اللهِ، فَإِذَا فَعَلُوا ذَلِكَ فَقَدْ مَنَعُوا مِنْكَ دِمَاءَهُمْ وَأَمْوَالَهُمْ، إِلَّا بِحَقِّهَا وَحِسَابُهُمْ عَلَى اللهِ».
[صحيح] - [رواه مسلم] - [صحيح مسلم: 2405]

Abu Hurayrah (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said on the Day of Khaybar:
"Verily, I shall give this banner to a man who loves Allah and His Messenger, and Allah will grant victory at his hands." ‘Umar ibn al-Khattāb said: I never liked leadership except on that day. He said: I kept showing myself in the hope that I might be called for it. He said: The Messenger of Allah (may Allah's peace and blessings be upon him) called ‘Ali ibn Abi Tālib and gave it to him and said: "Proceed and do not look back until Allah grants you victory." He said: ‘Ali walked for a while and then stopped without looking back and shouted: O Messenger of Allah, on what should I fight the people? He said: "Fight them until they testify that there is no god but Allah and that Muhammad is the Messenger of Allah. If they do so, their blood and properties become inviolable for you, except what is rightly justified, and their reckoning is with Allah."
[Authentic hadith] - [Narrated by Muslim] - [Sahih Muslim - 2405]

Explanation

The Prophet (may Allah's peace and blessings be upon him) informed the Companions that Muslims would win victory over the Jews of Khaybar, a city near Madīnah, the following day at the hands of a man whom he would give the banner, i.e., the flag that the army takes as its slogan. Among the traits of this man is that he loves Allah and His Messenger, and Allah and His Messenger love him.
‘Umar ibn al-Khattāb (may Allah be pleased with him) mentioned that he never liked the idea of leadership or being one meant except that day in the hope that he might be the one to win the love of Allah and His Messenger that the Prophet (may Allah's peace and blessings be upon him) mentioned. ‘Umar (may Allah be pleased with him) stretched his body to be seen by the Prophet (may Allah's peace and blessings be upon him), hoping that he would be called for that mission and out of keenness to take this banner.
The Prophet (may Allah's peace and blessings be upon him) called ‘Ali ibn Abi Tālib (may Allah be pleased with him) and gave him the banner and ordered him to proceed with the army and not to quit the fight after encountering his enemy, for rest, a pause, or a truce until Allah grants him victory and dominance over these fortresses.
‘Ali (may Allah be pleased with him) proceeded, then he stopped but without looking back so as not to disobey the Prophet's command. He raised his voice and said: O Messenger of Allah, on what should I fight the people?
He (may Allah's peace and blessings be upon him) said: Fight them until they testify that there is no god but Allah and that Muhammad is the Messenger of Allah. If they respond and embrace Islam, then their blood and properties become inviolable and unlawful for you except what is rightly justified, i.e., unless they commit a crime or felony for which they deserve to be killed in compliance with the rulings of Islam, and their reckoning is with Allah.