The word(s) "tranquillity" appears 6 time(s) in 6 verse(s) in Quran in Saheeh International translation.

(1) Then Allah sent down His tranquillity upon His Messenger and upon the believers and sent down soldiers angels whom you did not see and punished those who disbelieved. And that is the recompense of the disbelievers.

(2) If you do not aid the Prophet - Allah has already aided him when those who disbelieved had driven him out [of Makkah] as one of two, when they were in the cave and he said to his companion, "Do not grieve; indeed Allah is with us." And Allah sent down his tranquillity upon him and supported him with angels you did not see and made the word of those who disbelieved the lowest, while the word of Allah - that is the highest. And Allah is Exalted in Might and Wise.

(3) And of His signs is that He created for you from yourselves mates that you may find tranquillity in them; and He placed between you affection and mercy. Indeed in that are signs for a people who give thought.

(4) It is He who sent down tranquillity into the hearts of the believers that they would increase in faith along with their [present] faith. And to Allah belong the soldiers of the heavens and the earth, and ever is Allah Knowing and Wise.

(5) Certainly was Allah pleased with the believers when they pledged allegiance to you, [O Muhammad], under the tree, and He knew what was in their hearts, so He sent down tranquillity upon them and rewarded them with an imminent conquest

(6) When those who disbelieved had put into their hearts chauvinism - the chauvinism of the time of ignorance. But Allah sent down His tranquillity upon His Messenger and upon the believers and imposed upon them the word of righteousness, and they were more deserving of it and worthy of it. And ever is Allah, of all things, Knowing.