Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates that the Prophet (peace and blessings be upon him) said: "The prayer during sword-fighting (that is, the fear prayer) is one rak'ah; whichever direction the man is facing, it will suffice for him." The narrator says: I think he also said: He did that and did not repeat it.
Al-Bazzar recorded it; its chain contains Muhammad bin Abd al-Rahman al-Baylamani, who is extremely da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 3195