What is iʿtikāf? Why do Muslims spend the last ten nights of Ramadan in the masjid?

"I have fasted, and upon your provision I have broken my fast. Glory be to you and with your praise, O Allah, except from us, for you are the all-hearing, the all-knowing. Book of Itikaf. It is recommended to perform Itikaf. Itikaf should only be performed in a mosque where congregational prayers are held, and it is preferable to do it in a central mosque the itikaf spans days that include a Friday. Itikaf is valid without fasting but it is better to do it while fasting as it helps to focus the mind, aids in subduing the self, and aligns with the purpose of itikaf. Itikaf involves confining oneself to a specific place and adhering to it consistently. Allah"

"says in Surah Al-Anbiya, what are these statues to which you are devoted? It is a practice inherited from the Prophet Muhammad, peace be upon him and his companions, as the Prophet performed itikaf during the last ten days of Ramadan and continued to do so until Allah took his soul. He encouraged his companions to do the saying, whoever wishes to perform itikaf should do so during the last ten days. During itikaf, one should engage in activities that bring them closer to Allah, such as reciting the Quran, glorifying Allah, proclaiming his oneness, and reflecting. One should avoid speech and actions that"

"the reality of devoted retreat: his people's portion was retreat upon images, and his portion was retreat upon the Majestic Lord. Al-tamathil is the plural of timthal, meaning fashioned forms. So the heart's attachment to other than God, its preoccupation with that other and its leaning upon it, is a retreat on its part upon the images that have arisen within it — the very counterpart of retreat upon the images of idols. For this reason the idolatry of the worshippers of"

"Whoever's heart does not keep its retreat upon God alone keeps it upon images of every kind, as the leader of the upright said to his people: "What are these images to which you are so devoted?" So he and his people divided between them the reality of devoted retreat: his people's portion was retreat upon images, and his portion was retreat upon the Majestic Lord. Al-tamathil is the plural of timthal, meaning fashioned forms."

"idols lay in their devoting their hearts, their aspirations and their wills to their images. So when there are in the heart images that have taken possession of it and enslaved it, so that it keeps its retreat upon them, that is the counterpart of the idolaters' retreat upon their idols. For this reason the Prophet called such a man their slave, and prayed against him with wretchedness and downfall, saying: "Wretched is the slave of the dinar, wretched the slave of the dirham; wretched is he and cast down, and if he is pricked by a thorn, may it not" be plucked out."

"The Prophet, peace and blessings be upon him, said to his companions when they were shown the Night of Decree in the last ten nights: "I see your dreams have agreed on the last ten nights, so whoever is seeking it, let him seek it in the last ten nights of رَمَضَان." Dreams are like visions; some are merciful, some are psychological, and some are from شَيْطَان."

"The Prophet مُحَمَّد, peace be upon him, would seclude himself with a mat in the mosque during his retreat, being alone with his Lord, the Almighty, and would not engage in teaching or reminding the companions during that time. Therefore, it is well-known in the school of أَحْمَد and others that it is not recommended for the one in retreat to teach the القُرْآن and knowledge. Their seclusion for remembrance and worship is better for them, as evidenced by the actions of the Prophet, peace be upon him."

"Zaydi scholars and elders came to visit Sheikh Ahmad ibn al-Ajil, the Sheikh received them outside his retreat, and his companions greeted them while he remained in his place. They discussed the matter of Qadar, divine predestination, asserting that there is no predestination and that the responsible being creates his deeds. Sheikh Ahmad told them that if their claims were true, they should rise from their seats, but they could not. The Sheikh left them in their state, entered his retreat, and they felt the intense heat and the sun's glare. In their distress, the Sheikh's companions went to him, saying that these people had repented and abandoned their"

"built, one for men and the other for women. The sick seek healing from this bath and come to it from the farthest parts of the land, and there is a retreat for visitors who stay and are fed for three days. This retreat was built by one of the Turkmen kings. We lodged in this city at the lodge of Fatah Aki Shams al-Din, one of the dignitaries, and we coincided with the day of Ashura at his place, where he prepared much food and invited the army leaders and townsfolk at night."

"and urging for battle. However, our Lord, may Allah support him, advanced against his enemy alone, with his noble self, after knowing of the people's retreat and realizing that none remained with him to fight. At that point, terror fell into the hearts of the enemies, and they fled before him. It was one of the wonders, the retreat of nations before a single man. This is indeed the grace of Allah which he grants to whom he wills, and the outcome belongs to the pious. It is nothing but the fruit of what the Most High grants when relying on and delegating matters to Allah. Regarding his engagement with knowledge, here he is."