JAMRAT E AQBAH OR UQBAH OR KUBRA OR QUSWA
Jamrat is a Hajj ritual that involves stoning the three pillars that represent the devil (shaytan in Arabic). As part of this Hajj ritual, the pilgrims throw small pebbles at those three structures of Jamrat in the city of Mina. Pilgrims collect these pebbles at Muzadlifah. These pebbles (small stones) can also be collected in the city of Mina, east of Makkah. The process of casting or stoning of seven pebbles to these pillars is called as Rami or Ramee.
The major pillar which is nearly 300 meters on from Al-Khaif Mosque, is known as the pillar of Aqabah (Jamra e Uqbah). And this the only pillar which is stoned on 10th of Zilhijjah and also stoned with other 2 pillars on 11th 12th and 13th Zilhijjah during Hajj days. The other names of Jamrat e Aqbah are Jamrat e Uqba or Jamrat e Quswa or Jamrat e Kubra.
Stoning the Jamaraat is one of the obligatory rituals of Hajj and is prescribed for everyone who intends to do this great pilgrimage. This ritual is mentioned clearly in the Sunnah and its authenticity is agreed upon by the scholars.
The historical significance of Jamrat ritual hails from Prophet Ibraheem when the devil appeared to him three times. At each of the appearances, Angel Jibraeel (Gabriel) told Prophet Ibraheem (Abraham) to pelt the devil. Thus, the basis of the significance of the ritual.  
The first (minor) pillar called as Jamra e Ulaa is close to the Al-Khaif Mosque, 155 meters from the first pillar is the second (medium) pillar(Jamra e Wusta). The third (major) pillar, another 155 meters on, is known as the pillar of Aqabah (Jamra e Uqbah) which is discussed here. Pilgrims start the stoning with the minor pillar and then move on to the medium pillar and the major pillar. 
It was narrated from the Prophet (peace and blessings of Allaah be upon him) that he stoned Jamarat al-‘Aqabah which is al-Jamarah al-Quswa which is closer to Makkah, with seven pebbles, during the morning of the Day of Sacrifice, saying “Allaahu akbar” with every pebble which was a little bigger than a chickpea. Sahih al-Bukhari 1750
Ibn ‘Abbaas (may Allah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said to me on the morning of al-‘Aqabah when he was standing atop his camel: “Come and pick up for me.” So I picked up for him pebbles which were a little bigger than a chickpea. He put them in his hand and said, “With pebbles like this stone (the Jamaraat)… and beware of going to extremes, for those who came before you were destroyed because of going to extremes in religion.” Ibn Maajah 3029, Classed as saheeh by al-Albaani in Saheeh Ibn Maajah, 2455 
With regard to stoning the Jamaraat on the days of al-Tashreeq – the 11th, 12th and 13th of Dhu’l-Hijjah – that starts after the sun has passed its zenith – i.e., midday when the time for Zuhr begins – and lasts until nighttime. If it is too difficult because of overcrowding etc, there is nothing wrong with stoning the Jamaraat at night, until dawn. It is not permissible to stone the Jamaraat on the 11th, 12th and 13th before midday, because the Prophet (peace and blessings of Allaah be upon him) did not stone them until after midday, and he said to the people: “Learn from me your rituals (of Hajj).” Sahih Muslim 1297 and Sunan an-Nasa'i 3062. The fact that the Prophet (peace and blessings of Allaah be upon him) delayed stoning the Jamaraat until this time, even though it was very hot, and did not do it earlier in the day, when it is cooler and easier, indicates that it is not permissible to stone the Jamaraat before this time. This is also indicated by the fact that the Prophet (peace and blessings of Allaah be upon him) used to stone them from the time when the sun passed its zenith before he prayed Zuhr. This indicates that it is not permissible to stone the Jamaraat before the sun passes its zenith, otherwise doing that would be better so that one could pray Zuhr when its time began, because it is better to pray when the time for that prayer begins. The point is that the evidence indicates that stoning the Jamaraat on the days of al-Tashreeq is not permissible before the sun has passed its zenith. Fataawa Arkaan al-Islam, p. 560
The days of al-Tashreeq end at sunset on the 13th. However stoning during the day is better unless – because of the large numbers of pilgrims and their thoughtless attitude towards one another – one fears death, harm or unbearable hardship, in which case it is permissible to stone the Jamaraat at night and there is nothing wrong with that. If a person stones them at night even though he does not fear these things, there is also no harm in that, but it is better to be on the safe side in this matter and not stone them at night unless there is a need to do so. 
Ibn al-Mundhir (may Allaah be pleased with him) said: They were unanimously agreed that if a person stones the Jamaraat during the days of al-Tashreeq after the sun has passed the meridian, that is valid. AL-IJMAA’ BY IBN AL-MUNDHIR (11)
Ibn Hazm (may Allaah be pleased with him) said: They agreed that the three days after the Day of Sacrifice are the days for stoning the Jamaraat, and that the one who stoned them during those days after the meridian, that is valid. MARAATIB AL-IJMAA’ BY IBN HAZM (46)
Ibn Qudaamah (may Allaah have mercy on him) said: When he reaches Mina, he should start with Jamrat al-‘Aqabah, which is the furthest of the Jamaraat from Mina and the closest of them to Makkah, and it is at al-‘Aqabah, hence it is also called Jamrat al-‘Aqabah. He should stone it with seven pebbles, saying takbeer with each throw. He should stand at the middle of the valley and turn to face the qiblah, then he should leave and should not stay there. This is a summary of the views of those scholars whose views we know. Al-Mughni (3/218) 
There are many mistakes committed by some pilgrims when stoning the Jamaraat.
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