Overall Meaning: Meaning of tranquility:
Sakinah linguistically: It comes from sukun (stillness), the antonym of movement. Sakan al-shay’ (a thing has become still) if its movement dissipates. [287] al-Sihah, al-Jawhari (1/323); Maqayis al-Lughah, Ibn Faris (3/88); Lisan al-`Arab, Ibn Manzur (13/211).
Sakinah technically: It is tranquility and composure which Allah causes to descend upon the heart of his slave when scared or unstable. He is not disrupted thereafter from what befalls him, but rather it increases him in faith, certitude, and steadfastness. [288] Madarij al-Salikin, Ibn al-Qayyim (2/503).

Commandments of tranquility and encouragement towards it in the Sunnah:
❖ The Prophet ﷺ said, “When the call to establish the prayer is made, then do not rush towards it. Rather, walk to it, adhering to tranquility. Whatever you reach of it, pray; whatever passes you from it, complete.” [289] Reported by al-Bukhari (908) and Muslim (602), and the wording is his.
❖ Ibn `Abbas, Allah be pleased with them both, narrated, “I went forth with the Prophet ﷺ on the day of `Arafah. The Prophet ﷺ heard a great public outcry and the beating of camels behind him. So he beckoned to the people with his lash and said, ‘People, be tranquil. Righteousness is not reached through rushing.’” [290] Reported by al-Bukhari (1671).

Quotes of the Predecessors and scholars on tranquility:
❖ `Umar ibn al-Khattab, Allah be pleased with him, said, “Learn and teach the people, and learn composure and tranquility in seeking it.” [291] Reported by al-Bayhaqi in Shu`ab al-Iman (1789). Al-Bayhaqi said in al-Madkhal ila al-Sunan al-Kubra (2/153), “This is the authentic statement of `Umar. It is mentioned that it is narrated and raised to the level of the Prophet ﷺ, but this is weak.”
❖ Ibn al-Qayyim said, “If tranquility descends upon a heart, it finds rest. The limbs then become tranquil and abject due to this, and they acquire composure. It also allows the tongue to speak what is correct and wise, and it acts as a barrier between him and profanity, lewdness, frolic, obscenity, and every falsehood.” [292] Madarij al-Salikin, Ibn al-Qayyim (2/504).

Categories of tranquility:
General: As it affects all of creation. It is the type which one finds in fulfilling acts of worship. It begets abjectness, subordination, and presence of heart with Allah. It allows the slave to enact his slavehood with his heart and body, in devotion to Him, honoured and majestic. [293] A`lam al-Muwaqqi`in, Ibn al-Qayyim (4/155). 
Specific: This is the type which affects the followers of the Messengers depending on the degree of adherence they have to their way. It is the tranquility of faith, one that calms the heart when doubtful and uncertain. For this reason, Allah causes it to descend upon them when they are in most need of it: “It was He who made His tranquility descend into the hearts of the believers, to add faith to their faith. The forces of the heavens and earth belong to Allah; He is all knowing and all wise.” (al-Fath: 4) He mentioned his favour upon them through the forces that are external to them, as well those forces that penetrated them - serenity at the moment of anxiety and instability.

Benefits of tranquility:
❖ Tranquility is a cloak which is sent down to make wavering hearts secure, and calm unruly inhibitions.
❖ Its possessor is fulfilling the command of Allah’s Messenger ﷺ, “Tranquility, tranquility!” [294] Reported by Muslim (1218) from the extensive narration of Jabir ibn `Abdillah, Allah be pleased with them both.
❖ If tranquility comes down on a slave, his affairs will be rectified and set right, and his conscience will be at peace. If it departs, so will happiness, security, comfort, rest, and good living. [295] Madarij al-Salikin, Ibn al-Qayyim (2/207).
❖ He who adorns himself with tranquility is able to be abject in his prayer. This is because tranquility and abjectness in ablution are a prelude to the abjectness within the prayer.
❖ From its fruits is Allah loving the slave, and subsequently the people loving him.
❖ Gives the slave strength to bear calamities if they befall him.
❖ Allows the slave to absorb his anger in difficult situations.

Means to acquiring tranquility:
1- Following the command of the Prophet ﷺ, “Adhere to tranquility.” [296] Reported by al-Bukhari (1671) from the narration of Ibn `Abbas, Allah be pleased with them both. 2- Accompanying those of a calm demeanour. “Man is upon the way of his intimate friend. Let each of you consider whom they take as intimate friends.” [297] Reported by Abu Dawud (4833), al-Tirmidhi (2378), and Ahmad (8317) and this is his wording, from the narration of Abu Hurayrah, Allah be pleased with him. Al-Tirmidhi said, “It is sound, strange.” al-Nawawi authenticated its chain in Riyad al-Salihin (177). Ibn Hajar graded it as sound in al-Amali al-Mutlaqah (151).
3- Reading the Prophet's biography, ﷺ.
4- Knowing the benefits of tranquility and its impact.
5- Adorning oneself with patience.

Examples of tranquility:
❖ Among the characteristics of the Prophet ﷺ is his tranquility. It manifested in him as solemnity and poise, entrancing others to accept and submit. He used to be incredibly awe-inspiring, such that the messengers of Khosrow shrunk from his gravitas. Despite coming to him with the haughtiness of the Persians and the arrogance of tyrannical kings, he was still more tremendous in their souls, more impressive in their eyes, even though he was not vain nor imperious. He was characterised by his humility, and known for his modesty. [298] A`lam al-Nubuwwah, al-Mawardi (1/254), with adaptation.
❖ Imam Ahmad was characterised by serenity and composure. Al-Marrudhi said, “The poor were not more honoured than in the sittings of Ahmad. He used to lean towards them and away from those of the worldly life. He had forbearance, and he was not hasty. He was very humble, enshrouded by tranquility and poise. If he sat in his sitting after the afternoon prayer to issue religious verdicts, he did not speak until asked. Once he would leave to his mosque, he would do so pretentiously.” [299] Siyar A`lam al-Nubala’, al-Dhahabi (11/218).