It is narrated from Sayyiduna Salamah bin al-Akwa' (may Allah be pleased with him) that he said: In the time of the Messenger of Allah (peace and blessings be upon him) I took part in a military expedition under the command of Sayyiduna Abu Bakr (may Allah be pleased with him), and at that time the battle cry (shi'ar) of the Companions of the Prophet (peace and blessings be upon him) was 'Amit, amit' (Kill, kill). This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it.