المص ﴿۱﴾ كِتَابٌ أُنْزِلَ إِلَيْكَ فَلَا يَكُنْ فِي صَدْرِكَ حَرَجٌ مِنْهُ لِتُنْذِرَ بِهِ وَذِكْرَى لِلْمُؤْمِنِينَ ﴿۲﴾ اتَّبِعُوا مَا أُنْزِلَ إِلَيْكُمْ مِنْ رَبِّكُمْ وَلَا تَتَّبِعُوا مِنْ دُونِهِ أَوْلِيَاءَ قَلِيلًا مَا تَذَكَّرُونَ ﴿۳﴾

﴾1﴿ Alif-Laaam-Meeem-Saaad
﴾2﴿ Kitaabun unzila ilaika falaa yakun fee sadrika harajum minhu litunzira bihee wa zikraa lilmu'mineen
﴾3﴿ Ittabi'oo maaa unzila 'ilaikum mir Rabbikum wa laa tattabi'oo min dooniheee awliyaaa'a; qaleelam maa tazakkaroon

﴾1﴿ Alif-Laaam-Meeem-Saaad
﴾2﴿ This is a book that has been revealed to you, so there should be no hardship in your chest from its delivery so that you fear with it, and it is admonition for the believers
﴾3﴿ Follow what has been revealed to you from your Lord And don't follow, contrary to Allah Almighty from other friends, you accept very little advice

Relevancy: is that this surah is the one in which in Surah An'am, the issue of monotheism of rational reasons was stated So, in this surah, there are narrations on this issue and it mentions the bravery of the prophets to express monotheism -
Claim of this surah: First, be brave to express the issue of monotheism and the Qur'an (2) Second, follow the Qur'an and the Sunnah, and do not follow anything contrary to it, especially in Halal and Haram (3) Third, don't associate with Allah Almighty in servitude and to want is in verse (54) -
Summary of the surah: There are two chapters in this surah, the first chapter to verse (54) and three chapters in it, the first chapter to verse (10), It is mentioned in the first claim and the second claim that worldly fear is like mentioning the three states of the deniers in verses (5,4), And again, the fear of the afterlife is mentioned in three situations in verses (6, 7, 8) and again, persuasion is in verse (10) -

[1] About abrivations it has been explained in detail before, and here, with the letter Saad, there is a subtle reference to the many stories of this surah and to the omniscience of Allah Almighty.
[2] The point is that this book was revealed to express, so if there are tasks in expressing it, wait and don't be sad, In this verse, it is the first claim, in which the definition of the book, two benefits of the book and one of its etiquette are mentioned,  (لِتُنْذِرَ) (litunzira) It is common for polytheists and unbelievers and with believers, (ذِكْرَى) (zikraa) It is special for believers -
[3] This is the second claim, this is the quality of warning and reminder, (مَا أُنْزِلَ) (maaa unzila) are Qur'an and Sunnah, Khazan, Qurtubi have all said that which book or saint or Mullah etc. is against it, so don't follow it - (أَوْلِيَاءَ) (awliyaaa'a) Wilayat is meant to follow accompanied by love - Qurtubi said that whoever was satisfied with a religion, then he became a member of that religion and the people of that religion became his friends, (قَلِيلًا مَا تَذَكَّرُونَ) (qaleelam maa tazakkaroon) This means that there are very few owners of this attribute in the world -