إِذْ تَسْتَغِيثُونَ رَبَّكُمْ فَاسْتَجَابَ لَكُمْ أَنِّي مُمِدُّكُمْ بِأَلْفٍ مِنَ الْمَلَائِكَةِ مُرْدِفِينَ ﴿۹﴾ وَمَا جَعَلَهُ اللَّهُ إِلَّا بُشْرَى وَلِتَطْمَئِنَّ بِهِ قُلُوبُكُمْ وَمَا النَّصْرُ إِلَّا مِنْ عِنْدِ اللَّهِ إِنَّ اللَّهَ عَزِيزٌ حَكِيمٌ ﴿۱۰﴾

﴾9﴿ Iz tastagheesoona Rabbakum fastajaaba lakum annee mumiddukum bi alfim minal malaaa'ikati murdifeen
﴾10﴿ Wa maa ja'alahul laahu illaa bushraa wa litatma'inna bihee quloobukum; wa man nasru illaa min 'indil laah; innal laaha Azeezun Hakeem

﴾9﴿ When you cried out to your Lord for help, He answered you, “I will aid you with a thousand angels, coming one after another.”
﴾10﴿ And Allah did not make this (sending of the angels) except as good news, and so that your hearts might be strengthened by it. And victory is only from Allah. Surely, Allah is Mighty, Wise.

[9] This is the third reason for the first claim. Its summary is that the Messenger of Allah (May Allah bless him and give him peace) turned toward the qibla, raised his hands, and began supplicating. In that supplication, he said: (Allahumma anjiz li ma wa'adtani, Allahumma atini ma wa'adtani, Allahumma in tuhlik hadhihi al-'isabata min ahl al-Islam, la tu'bad fil-ard) (O Allah, fulfill for me what You have promised me. O Allah, give me what You have promised me. O Allah, if You destroy this group of Muslims, You will not be worshipped on earth).
So Allah, the Exalted, accepted this supplication and sent one thousand (1000) angels, and through them, victory and spoils were obtained. Therefore, do not dispute over the spoils.
"(Idh tasta'ithun)" is derived from "ghawth" (help), and "ghawth" refers to crying out and seeking assistance. This verse is clear evidence that seeking aid (istighatha) is exclusive to the Lord.
"(Mumiddukum)" in the context of help, implies both support and increase.
"(Murdifin)" means the angels came one after another in succession, and such a manner of arrival strikes great terror into the hearts of the enemies. This way of angelic descent occurred in Badr.
In verse 124 of Surah Aal-e-Imran, their descent is mentioned, which indicates that the angels were heavenly beings. In verse 125 of the same Surah, their military signs are mentioned with "musawwimin" (marked).
[10] This means that in apparent assistance (by the angels) there are two benefits: one is reassurance of the heart, and the other is the pleasant effects on the face. This answers a question—namely, if someone were to assume that help comes from the power of the angels, then the answer is given in the verse: "Wa ma an-nasru..." (And victory is not except from Allah).
This has two meanings: First, assistance within the means—this is the attribute of creation, like in verse 152 of Surah Aal-e-Imran and in verse 22 of this Surah.
Second, assistance beyond the means—that is exclusive to Allah the Exalted, and it refers to dominance (ghalaba), which is the intended meaning in this verse. A similar verse is in verse 126 of Surah Aal-e-Imran.
The difference is: in that verse, "lakum" (for you) is mentioned, while it is not mentioned here.
The second difference is that there, "bihi" (through it) is mentioned after "liyaṭma'inna qulubukum" (so your hearts may be reassured), whereas here it is mentioned before, because here the cause (i.e., the sending of a thousand angels) is mentioned first. Therefore, through "bihi", the causal relationship is expressed from the outset.