It was called after the Companion Umair Al-Khatamy. In this campaign, a poet who kept inciting against the Muslims by/attack them using words??s her words and actions was killed.
The mission took place in Ramadan in the 2nd year of Hijra, in one of the houses of Banu Khatamah in Medinah.
The poet Asma bint Marwan used to keep inciting other against P, Islam, and the Muslims.
The leader of the mission was Umair ibn Adi Al-Khatamy, who was the first person from Banu Khatamy who embraced Islam. He was a reciter of the Quran who has weak eye-sight. Some reports state that P did not order the mission to be launched, but after the battle of Badr he () wished it would happen. Another report staes that P said, <‘Is there anyone who can deal with her (i.e. Asma bint Marwan) for me?’ Consequently, Umair said, ‘I will deal with her.’>
Asma was married to one from Banu Khatamah. Her husband was Marathad ibn Zayd ibn Haseen Al-Ansari, who later embraced Islam. Asma kept talking badly about P, and kept harming him and the Muslims. It is said she used to prevent them fron going to??s the mosque and place things that harmed them in their way (eg. rags covered in menstrual blood??s). The reports differ about how she was killed. According to the Prophet’s biography from a report of Al-Waaqidi, Umair went to her in the middle of the night and plunged the sword into her chest until it came out of her back. He then prayed Fajr Prayer with P in Medinah, after which P asked him, <‘Did you kill the daughter of Marwan?’ Umair replied, ‘Yes. Is there any sin on me because of that’ P answered, ‘The validity of what you have done is something that no one could dispute.’>
It has been reported that Omar ibn Al-Khattab said, “Look at the blind person who led an operation/is quick in obeying Allah??s in obedience to Allah??.” Upon this, P said, <Do not say a blind person, but a person with insight.>
Another report related that Umair went to Asama when she was selling dried dates, and killed her. When Umair returned to the houses/house??s of Banu Khatamah, he saw her son among a group of people who were burying her. They asked him, “Oh Umair, did you kill her?” He replied, “Yes. So all of you join together to make plans against me, and do not be slow in carrying out your plans. By Him in Whose hands is my soul, if all of you say what she used to say, I will hit you with this sword until I die or I kill you all.” After that day, the Muslims of Banu Khatamah stopped hiding their faith, although anyone from them who had embraced Islam before that day used to hide their faith.
This was the stage in which Allah gave permission to the Muslims to reply to the harm they suffered from those who fought Allah and His Messenger. If we consider the cases of those who were killed, we will realize that they were people who used to fight Allah and His Messenger; they were not just disbelievers in Islam.