Allah says in surah al-Ma'idah:

 Allah says in surah al-Ma'idah:

*يَا أَيُّهَا الَّذِينَ آمَنُوا اذْكُرُوا نِعْمَتَ اللَّهِ عَلَيْكُمْ إِذْ هَمَّ قَوْمٌ أَن يَبْسُطُوا إِلَيْكُمْ أَيْدِيَهُمْ فَكَفَّ أَيْدِيَهُمْ عَنكُمْ ۖ وَاتَّقُوا اللَّهَ ۚ وَعَلَى اللَّهِ فَلْيَتَوَكَّلِ الْمُؤْمِنُونَ*

*O you who have believed, remember Allah's favors on you when a people planned to extend their hands against you but He restrain their hands from you. And have taqwa of Allah. And let the believers put their reliance on Allah. [11]*

There are a number of reports about the specific circumstances which this ayah is referring to. Ibn Juzay summarized these in his tafsir by writing:

There are four opinions about the circumstances behind the revelation of this ayah.

The first is that it refers to when the Prophet went to the Jewish tribe of Banu al-Nadhir and they planned to kill him by dropping a large stone on him, so Jibril told him about this and he got up and left. This explanation is strengthened by the fact that the following ayaat are speaking about the betrayals of the Jews. 

The second position is that this ayah is in reference to the incident on the bedouin who brandished a sword against Allah's Messenger when he found him alone on a journey and said to him, "Who can protect you from me?" to which the Prophet said, *"Allah!"* at which the bedouin - whose name was Ghawrath ibn al-Harith al-Muharibi al-Ghatfani - put his sword away and sat down.

The third position is that this ayah is referring back to when the disbelievers' planned to strike the Muslims and so the salat al-khawf was revealed. 

The fourth position is that this ayah applies to any circumstance in which Allah protected the Muslims from the disbelievers. 

[Tashil li-'Uloom al-Tanzil under surah al-Ma'idah ayah 11] 

In his tafsir, sheikh 'Abd al-Rahman al-Sa'di characteristically took the fourth and most expansive interpretation of the ayah and then highlighted the main takeaways by writing:

This is aid from Allah to His believing servants, so they ought be grateful to Allah for it and worship and remember Him. 

This ayah applies to anyone - whether it be a disbeliever, munafiq or transgressor - who intended to harm the believers and then Allah held back that harm from the Muslims. Any instance of that falls under the meaning of this ayah.

Allah then commanded them to seek His assistance in gaining victory against their enemies, and to ask His assistance in all of their affairs, for He said, *"And let the believers put their reliance on Allah."*

[Taysir al-Karim al-Rahman pg 246]