Abdullah bin Abbas reported,

When the Prophet ﷺ was driven out of Mecca, Abu Bakr said, "They have driven out their Prophet. Indeed, we belong to Allah and to Him we shall return. They will surely be destroyed."Then this verse was revealed, "Permission has been granted to those who are being fought, because they have been wronged, and indeed Allah is fully capable of granting them victory" [Hajj 22:39].Abu Bakr said, "I knew then that there would be fighting."Ibn Abbas said, "This is the first verse revealed concerning fighting."

Azami 12806

Sahih

عن ابن عباس قال

لما أخرج النبي ﷺ من مكة قال أبوبكر: أخرجوا نبيهم، إنا لله وإنا إليه راجعون، ليهلكن، فنزلت: {أذن للذين يقتلون بأنهم ظلموا وإن الله على نصرهم لقدير}، فعرفت أنه سيكون قتال. قال ابن عباس: فهي أول آية نزلت في القتال.

الأعظمي 12806صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Tafsir of the great Quran
Chapter
Tafsir of Surah Anbiya
Section
His saying, "Permission has been granted to those who are being fought because they were wronged, and indeed Allah is able to give them victory. Those who have been expelled from their homes unjustly, only because they say our Lord is Allah. And were it not that Allah checks the people, some by means of others, there would have been demolished monasteries, churches, synagogues, and mosques in which the name of Allah is much mentioned. And Allah will surely support those who support Him. Indeed Allah is Powerful, Exalted in Might."
Numbering
Jami al-Kamil 12806 (2nd edition)
Azami 12806