Then Lord Allah sent down His Tranquility upon His Messenger and the believers, and sent down forces which you didn’t see, and punished those who disbelieved, and that is the reward for the disbelievers.
It is told in verses 41: 30-32 that indeed, those who declared that their Lord is Allah and have steadfast in that state, upon them Angels will descend saying: "you do not fear and you do not grieve, and you be happy with glad tidings of Paradise which you were promised. We are your patron both in this world and in the Hereafter. There is the Paradise, in which you will have whatever your soul desires and whatever you ask for; as a hospitable gift from Lord Allah, the Oft-Forgiving, the Most-Merciful”. Verse 48: 4 says: “It is He Who sent down tranquility into the hearts of the believers to increase faith along with their current faith; And to Lord Allah belongs the soldiers of the heavens and the earth, and Allah is the All-Knowing, the Wise”. It is told in verse 48: 18 “Surely, Lord Allah was pleased with the believers when they pledged with the Messenger under the tree during Hudayybiya Treaty, and He knew what was in their hearts, so He sent down tranquility upon them and rewarded them with an imminent triumph”. It is told in verse 48: 26: When those who disbelieved put into their hearts heat and transgression – heat and transgression of ignorance; but Allah sent down His tranquility upon His Messenger and upon the believers and firmed them with the word of heedfulness, and they were more deserving It and the people of It, and Allah is the Knower of everything”. With Adhikr which is the Best Interpretation of Lord's Book mentioned in verse 25: 33, one will get peace and tranquility. Verse 13: 28 ends as: Know that with the remembrance of Allah with Adhikr, the hearts will achieve peace and tranquility. See explanation 3: 10-12, 102, 154 and 8: 11.