As they approached the fortress, a Jewish warrior, by the name of Marhab, came out to challenge them. Marhab was a warrior who was renowned for his strength and bravery. Hence, when Marhab faced Hazrat ‘Ali (radhiyallahu anhu) and the Muslims, he began to boast over his bravery and great valour in battle by reciting the following couplets:
قَدْ عَلِمَتْ خَيْبَرُ أَنِّيْ مَرْحَبُ
The people of Khaibar all know well that I am Marhab
شَاكِيْ السِّلَاحِ بَطَلٌ مُجَرَّبُ
I am a warrior who is well-armed and experienced in warfare
إِذَا الْحُرُوْبُ أَقْبَلَتْ تَلَهَّبُ
(I show my true strength and valour) at the time when the fighting commences and the battle flames up and intensifies
Saying these words, he threw a challenge to the Muslims. In response to his challenge, Hazrat ‘Aamir bin Akwa’ (radhiyallahu anhu) came out. Hazrat ‘Aamir (radhiyallahu anhu) faced Marhab and recited the following couplets:
قَدْ عَلِمَتْ خَيْبَرُ أَنِّيْ عَامِرُ
The people of Khaibar all know well that I am Aamir
شَاكِيْ السِّلَاحِ بَطَلٌ مُغَامِرُ
I am a warrior who is fully-armed and I am prepared to plunge headlong into any battle
The duel then commenced with Marhab striking first. He swung his sword towards Hazrat ‘Aamir (radhiyallahu anhu), who blocked the strike with his shield. The strike of Marhab's sword was so powerful that as it struck the shield, it became embedded in it. Hazrat ‘Aamir (radhiyallahu anhu) seized this opportunity to strike Marhab from beneath his shield. However, he missed Marhab and his sword returned towards him, striking him and causing him a fatal injury.
Thereafter, Hazrat ‘Ali (radhiyallahu anhu) came out to challenge to Marhab. Marhab again recited the same couplets, to which Hazrat ‘Ali (radhiyallahu ‘anhu) responded by reciting the following:
أَنَا الَّذِيْ سَمَّتْنِيْ أُمِّيْ حَيْدَرَهْ
I am the one whose mother named him Haydar (the Fierce Lion)
كَلَيْثِ غَابَاتٍ كَرِيْهِ الْمَنْظَرَهْ
Like a fierce-looking lion of the jungle
أُوْفِيْهِمْ بِالصَّاعِ كَيْلَ السَّنْدَرَهْ
When I have to give an exchange, then I give full measure (i.e. my blow is complete and I kill the enemy swiftly and immediately)
In regard to Hazrat ‘Ali (radhiyallahu ‘anhu) referring to himself as Haydar (the fierce lion), it is reported that when Hazrat ‘Ali (radhiyallahu ‘anhu) was born, his father, Abu Taalib, was gone out on a journey and was not present in Makkah Mukarramah. Hence, his mother named him Haydar, after her father, whose name was Asad (which also means lion). When Abu Taalib returned to Makkah Mukarramah from his journey, he named his child ‘Ali. Thereafter, Hazrat ‘Ali (radhiyallahu ‘anhu) became known by the name given to him by his father. However, on this occasion, he referred to himself using the name given to him by his mother.
According to one narration, Marhab had a dream the previous night in which he saw that he was being torn apart by a lion. ‘Allaamah Zurqaani (rahimahullah) has mentioned that Hazrat ‘Ali (radhiyallahu ‘anhu) was blessed with knowledge of this through kashf (inspiration, either via a dream or some other way). It is for this reason that he referred to himself using the name Haydar, which meant fierce lion, in his couplets. Through referring to himself as a fierce lion, Marhab realized that his dream had indicated towards him meeting his end at the sword of Hazrat ‘Ali (radhiyallahu ‘anhu). This caused him to be overcome by fear and lose courage.
They then commenced the duel, and in a single blow, Hazrat ‘Ali (radhiyallahu ‘anhu) split the skull of Marhab, the ‘famous’ champion of Khaibar, and ended his life. Allah Ta‘ala then blessed Hazrat ‘Ali (radhiyallahu ‘anhu) with the conquest of this fortress.
(Saheeh Bukhaari #4210, Saheeh Muslim #1807, Majma’uz Zawaa’id #10206, Fat-hul Baari 7/535-549, Sharun Nawawi vol. 12 pg. 185 and Sharhuz Zurqaani 3/244-258)