Surah 4. An-Nisaa', Ayah 102

Lit., "among them". The "thou" in this sentence refers, primarily, to the Prophet and, by implication, to the leader of every group of believers at war with "those who deny the truth".

Lit., "when they have prostrated themselves, let them [i.e., the other group] be behind you". This idomatic expression is not to be taken literally: in classical Arabic usage, the phrase kana min wara'ika (lit., "he was behind thee") signifies "he protected thee" or (in military parlance) "he covered thee", and is not meant to describe the physical relative position of the two persons or groups.

Lit., "turn upon you in one turning".

I.e., if there is a risk of their weapons being damaged by exposure to unfavourable weather conditions, the warriors are exempted from the obligation of keeping their arms with them while praying. This exemption applies, of course, only to such of the soldiers as are in charge of particularly sensitive weapons; and the same applies to the individual cases of illness mentioned in the sequence. It must, however, be remembered that the term matar (lit., "rain") is often used in the Qur'an to denote "an affliction": and if we adopt this meaning, the above phrase could be rendered as "if you suffer from an affliction" - thus allowing for a wide range of possible emergencies.

 When the first group prays, the second group stands guard behind them, then the first group withdraws to the back when they finish their prayers and stand guard when the second group moves up to pray.

The congregational prayer in danger in face of the enemy rests on the principle that the congregation should be divided into two parties; one party prays while the other watches the enemy, and then the second party comes up to prayers while the first falls back to face the enemy; either party does only one or two Rakats, or about half the congregational prayer; every precaution is taken to prevent a rush by the enemy; even while at prayers armour and arms need not be put off except when rain is likely to cause inconvenience to the wearer and damage to the arms, or when illness or fatigue causes the wearer's strength to fail. Details can be varied according to circumstances, as was actually done by the Prophet at different times.