بَلَى إِن تَصْبِرُواْ وَتَتَّقُواْ
But if you hold on to patience and have Taqwa,
means, if you observe patience while fighting the enemy, all the while fearing Me and obeying My command.
وَيَأْتُوكُم مِّن فَوْرِهِمْ هَـذَا
and they will come rushing,
Al-Hasan, Qatadah, Ar-Rabi and As-Suddi said that Allah's statement means,
they (angels) will rush to you instantaneously.
Al-Awfi said that Ibn Abbas said that the Ayah means,
"All at once."
It is also said that;
it means, before their anger subsides (against the disbelievers).
The Second View;
The second opinion stipulates that the promise mentioned here (concerning the angels participating in battle) is related to Allah's statement,
وَإِذْ غَدَوْتَ مِنْ أَهْلِكَ تُبَوِّىءُ الْمُوْمِنِينَ مَقَاعِدَ لِلْقِتَالِ
(And (remember) when you left your household in the morning to post the believers at their stations for the battle) (3;121) of Uhud.
However, we should add, the angels did not come to the aid of Muslims at Uhud, because Allah made it conditional,
بَلَى إِن تَصْبِرُواْ وَتَتَّقُواْ
(But if you hold on to patience and have Taqwa), (3;125).
The Muslims were not patient at Uhud. Rather, they ran away and, consequently, did not receive the support of even one angel.
Allah's statement,
يُمْدِدْكُمْ رَبُّكُم بِخَمْسَةِ الافٍ مِّنَ الْمَليِكَةِ مُسَوِّمِينَ
your Lord will help you with five thousand angels having marks,
of distinction.
Abu Ishaq As-Subay`i said; from Harithah bin Mudarrib said that Ali bin Abi Talib said,
"The angels were distinguished by wearing white wool at Badr."
The angels also had special markings distinguishing their horses.
Allah said