The word as it is recited in the Quran: Mahmoud Khalil Al-Hussary, Al-Fath 48:4.
Sakina in Islam
The word occurs six times in the Quran: “It is He who sent down tranquillity into the hearts of the believers, that they might add faith to their faith” (48:4); and, in the cave, “Allah sent down His tranquillity upon him” (9:40). The Prophet ﷺ said that people gathered in a mosque to recite and study the Book of Allah have tranquillity descend upon them (Muslim 2699).
Meaning of the name Sakina
Sakina comes from the root s-k-n of rest and calm (sukun, “stillness”; sakan, “home”): it is tranquillity, the inner peace that drives away anxiety. In the Quran it is a peace that Allah sends down into the hearts of the believers. The name was borne by Sakina, daughter of al-Husayn, famed for her wit.
It is He who sent down tranquility into the hearts of the believers that they would increase in faith along with their [present] faith. And to Allāh belong the soldiers of the heavens and the earth, and ever is Allāh Knowing and Wise.
If you do not aid him [i.e., the Prophet (ﷺ)] - Allāh 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 [i.e., Muḥammad (ﷺ)] said to his companion, "Do not grieve; indeed Allāh is with us." And Allāh sent down His tranquility upon him and supported him with soldiers [i.e., angels] you did not see and made the word of those who disbelieved the lowest, while the word of Allāh - that is the highest. And Allāh is Exalted in Might and Wise.
And their prophet said to them, "Indeed, a sign of his kingship is that the chest will come to you in which is assurance from your Lord and a remnant of what the family of Moses and the family of Aaron had left, carried by the angels. Indeed in that is a sign for you, if you are believers."
Then Allāh sent down His tranquility upon His Messenger and upon the believers and sent down soldiers [i.e., angels] whom you did not see and punished those who disbelieved. And that is the recompense of the disbelievers.
"Whoever relieves a believer from one of the hardships of this world, Allah will relieve him from one of the hardships of the Day of Judgment. Whoever makes things easy for someone in difficulty, Allah will make things easy for him in this world and the Hereafter. Whoever covers a Muslim, Allah…