Muhammad ibn Maslamah, sometimes surnamed Ansari (591-666) (Arabic: محمد بن مسلمة الأنصاري) was a Companion of Muhammad.
He was among the first in Yathrib to become a Muslim and was a halif or an ally of the Aws tribe in Medina indicating he was not an Arab. He became a Muslim at the hands of Musab ibn Umayr, before Usayd ibn Hudayr and Sad ibn Muadh who were influential men in the city.
In 622 when Muhammad arrived in Medina he paired off each Muhajir with one of the Ansar, joining Muhammad ibn Maslamah with Abu Ubaida bin al Jarrah. Muhammad ibn Maslamah took part in all the military engagements of Muhammad except the Battle of Tabouk. On that occasion, he and Ali were put in charge of an army which was left behind to protect Medina. Later in life, he would related these battles to his ten children.
In 624, Muhammad ibn Maslamah volunteered when the Prophet Muhammad called upon his followers to kill Ka'b, a chief of the Banu Nadir, who had written poetry the Muslims found offensive. Muhammad ibn Maslama collected four others, including a foster-brother of Ka'b. By pretending to have turned against Muhammad, they enticed Ka'b out of his fortress on a moonlight night for what was supposed to be negotiations of Ka'b's sale of food to them. After Ka'b walked out of his fortress to meet Muhammad ibn Maslama and his companions, they attacked Ka'b and killed him in spite of his vigorous resistance.
Before the battle of Uhud, Muhammad and the Muslim force numbering some seven hundred persons spent a night in an open camp. He put fifty men under the command of Muhammad ibn Maslamah and entrusted him with patrolling the camp at night. During the battle itself, after the disastrous rout of the Muslims by the Quraish, a small band defended Muhammad till the tide of battle turned. Muhammad ibn Maslamah was among them.
In 627, after the surrender of the Banu Qurayza, Muhammad ibn Maslamah was put in charge of the captured males that were eventually killed.
During the caliphate of Umar (634 - 644), Muhammad ibn Maslamah was put in charge of a special office established to investigate complaints against officers of the state. When Amr ibn al-Aas requested reinforcements during his expedition to Egypt, Umar sent him four detachments of one thousand men each, led by Muhammad ibn Maslamah, az-Zubayr ibn aI-Awwam, Ubadah ibn as-Samit and al-Miqdad ibn al-Aswad.
Muhammad ibn Maslamah also served Umar's successor, the third "Rightly Guided Caliph", Uthman. When the latter was killed in 656 and civil war broke out Muhammad did not participate, deliberately breaking the sword he always used, and which was given to him by the Prophet. During this time, he was known as the "Knight of the Prophet" and by refusing to use the sword against Muslims he preserved this reputation.
Muhammad ibn Maslamah died in Medina, April 666 at the age of seventy five.
His brother Mahmoud ibn Maslamah was killed in the Battle of the Trench.
He was involved in the expulsion of the Banu Nadir from Medina
He was married and fathered two sons.