It has been narrated on the authority of Jabir who said: We were one thousand and four hundred on the Day of Hudaibiya. We swore fealty to hiin (the Holy Prophet) and 'Umar was holding the latter's hand (when he was sitting) under the tree (called) ahadeeth (to administer the oath to the Companions). The narrator added: We took oath to the effect that we would not flee (from the battlefield if there was an encounter with the Makkahns), but we did not take oath to fight to death.
´Jabir said:` "We did not give our pledge to the Messenger of Allah for death, rather we pledged not to flee (from battle)."
Hafiz Muhammad Ameen
The meaning of pledging allegiance unto death is also this: that we will remain steadfast and will not flee, even if circumstances of death arise. The intent of Hazrat Jabir radi Allahu anhu is that, at the time of pledging allegiance, we did not say, "even if we die." We only said that we will not flee. However, in meaning and outcome, there is no difference. Some people have also used the word "death," saying that we will not flee, even if death comes, as is explicitly stated in the following narration.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 4163