بَرَاءَةٌ مِنَ اللَّهِ وَرَسُولِهِ إِلَى الَّذِينَ عَاهَدْتُمْ مِنَ الْمُشْرِكِينَ ﴿۱﴾

﴾1﴿ Baraaa'atum minal laahi wa Rasooliheee ilal lazeena 'aahattum minal mushrikeen

﴾1﴿ This is a declaration of disassociation from Allah, the Exalted, and His Messenger to those among the polytheists with whom you made a covenant (and who have broken the covenant).

Relevancy: This, in connection with the previous surah, has several explanations. The first explanation is that since the rule of jihad was stated in Surah Al-Anfal, in this surah, there is an announcement of jihad. The second explanation is that in Surah Al-Anfal, it was merely an announcement of jihad, whereas in this surah, the groups with whom jihad can be undertaken are mentioned.
Claim of this surah: Fighting against the polytheists and the People of the Book, and striving against the hypocrites, are mentioned six times in the verses (123, 73, 36, 29, 14, and 5). And the matter of monotheism (tawheed) is mentioned at the end of the surah.
Summary of the surah: This surah is divided into four parts: In the first part, the fighting against the polytheists is mentioned; in the second part, the fighting against the People of the Book is mentioned; in the third part, the faults of the hypocrites are discussed; and in the fourth part, the characteristics of the believers are described. The first part extends up to verse 28, in which three types of polytheists are mentioned, four objections to fighting are refuted, thirteen reasons for fighting are listed, and encouragement towards jihad is given.
Note: The primary reason for not writing "Bismillah" at the beginning of this surah is that "Bismillah" was not revealed at the start of this surah. The second reason is based on the narration of Uthman (may Allah be pleased with him), as related by Tirmidhi and Abu Dawud, and reported by the author of Mishkat on page 194. The summary is that placing this surah after Surah Al-Anfal was a matter of scholarly judgment, based on the likelihood that this surah is a continuation of the previous one due to their strong connection; for this reason, "Bismillah" was not written at the beginning of the surah. Another possibility is that if the surah is considered independent, its name is written at the start. Another wisdom behind not writing "Bismillah" is that "Bismillah" denotes security, whereas this surah is about removing security (declaring war). A second wisdom is that, for example, when a declaration of war was sent to someone, "Bismillah" would not be written at the top.

[1] In this verse, the first group of polytheists is mentioned, called the “fighters” (muharibīn) because they broke the covenant. This includes those with whom the covenant was not time-limited. One ruling related to this is disassociation (bara’ah), which means removing any form of security and protection (dhimmah) and severing all ties. This concept is explained in the verses (113, 73, 36, 28, 23, 17, 15, 12, 5).