سنن النسائي

Abu Hurairah said: "The Messenger of Allah (ﷺ) was camping between Dajnan and 'Usfan, besieging the idolaters. The idolaters said: 'These people have a prayer that is dearer to them than their sons and daughters. Plan it, then strike them with a single heavy blow.' Jibril, peace be upon him, came and told the Messenger of Allah (ﷺ) to divide his companions into two groups, then lead one group in prayer while the others faced the enemy, on guard and with weapons at the ready. So he led them in praying one rak'ah, then they moved back and the others moved forward, and he led them in praying on rak'ah, so that each one of them had prayed one rak'ah with the Prophet (ﷺ) and the Prophet (ﷺ) had prayed two rak'ahs."