Quran 4:101 — Women (Al-Nesa')

When you travel, during war, you commit no error by shortening your Contact Prayers (Salat), if you fear that the disbelievers may attack you. Surely, the disbelievers are your ardent enemies.

[4:100] Anyone who emigrates in the cause of GOD will find on earth great bounties and richness. Anyone who gives up his home, emigrating to GOD and His messenger, then death catches up with him, his recompense is reserved with GOD. GOD is Forgiver, Most Merciful.

[4:102] When you are with them, and lead the Contact Prayer (Salat) for them, let some of you stand guard; let them hold their weapons, and let them stand behind you as you prostrate. Then, let the other group that has not prayed take their turn praying with you, while the others stand guard and hold their weapons. Those who disbelieved wish to see you neglect your weapons and your equipment, in order to attack you once and for all. You commit no error, if you are hampered by rain or injury, by putting down your weapons, so long as you remain alert. GOD has prepared for the disbelievers a shameful retribution.