Today we find a multitude of flags in the Muslim world. These have been carefully designed with colours and symbols to represent characteristics of the nation state. In Islam, we have not been given a choice concerning what type of flag we use even down to the colour. The shariah has specified the type of official flag the Khilafah will use and therefore we cannot deviate from this. Furthermore, we cannot wave flags that represent concepts which are against Islam such as nationalism and division of Muslim lands. The article below is taken from the book "Institutions of State in the Khilafah" by Hizb ut-Tahrir.
The State has flags (Alwiyah) and banners (Rayat) as deduced from the flags and banners of the first Islamic State, which the Messenger of Allah صلى الله عليه وسلم established in al-Medina al-Munawwarah. These will be as follows:
Definition of the Flag and Banner
The flag and banner, are linguistically called alam. Al-Qamus al-Muhit mentions under the root (r/w/y) that al-raya is 'al-alam, plural being rayaat. It mentions under the root (l/w/y) that al-liwa' is al-'alam, plural alwiyah.
The shariah designated each one of these terms a shar'i meaning as follows:
The flag (liwaa')
The flag (liwaa') is white, on which it is written 'la ilaha illa Allah, Muhammad Rasul Allah' with black script. It is tied to the amir of the army or the leader of the army. It is used as a sign of his location, and it goes along with this location. The evidence to tying the flag to the amir of the army is that the Prophet صلى الله عليه وسلم entered Makkah on the day of its conquest while raising a white flag. This was narrated by Ibn Majah through Jabir. An-Nasa'i also narrated through Anas that when the Prophet صلى الله عليه وسلم appointed Usama ibn Zayd as amir to the army for invading the Romans, he tied his flag with his own hands.
The banner (rayah)
The banner (rayah) is black, on which it is written 'la ilaha illa Allah, Muhammad Rasul Allah' with white script. It is carried by the leaders of the army divisions, regiments, detachments, and other army units. The evidence is that the Messenger صلى الله عليه وسلم , while being the leader of the army in Khaybar, he said: "I will give the Raya tomorrow to a man who loves Allah and His Messenger, and Allah and His messenger love him; and he gave it to 'Ali". This hadith is agreed upon. Ali (ra) was considered the leader of a division or a regiment in the army.
Al-Harith b. Hassan b. Al-Bakri also said in the hadith, "We came to Medina and we saw the Prophet صلى الله عليه وسلم on the Mimbar, with Bilal standing in front of him wearing his sword. There were black banners in front of the Messenger صلى الله عليه وسلم. I asked 'what are these banners?' They said: 'it is Amr b. al-'As who has just arrived from an expedition'".
"And there were black banners (rayaat)" this means there were many banners carried by the army though its amir was one, which was Amru ibn Al-Ass. This indicates there is one flag (liwaa') in the same army, but the banners (rayaat) are many in each army.
Thus, the flag (liwaa') is a sign ('alam) to the amir of the army only, while the banners (rayaat) are signs (a'lam) carried by the soldiers.
The flag (liwaa') is tied to the amir of the army
The flag (liwaa') is tied to the amir of the army, and it is a sign indicating the headquarters of the amir of the army. However, in the battle field, the leader of the battle, whether he is the amir of the army or appointed by him, is given the banner (rayah) to carry during the fight in the battle field. Therefore, the banner is called the mother of the war because it is carried by the battle leader in the battle field.
Therefore, at the time of actual war there will be one banner with every leader of a battle, a matter that was familiar at that time. Keeping the banner flying up was evidence to the might of the leader of the battle. This is an administrative order that is followed in accordance with the traditions of fighting in the armies.
The Messenger of Allah صلى الله عليه وسلم said announcing to the people the death of Zayd, Ja'far and Ibn Ruwahah before the soldiers brought the news: "Zayd took the banner (raya) but he was hit; and then Ja'far took it and he was hit; and then Ibn Ruwahah took it and he was hit" [Bukhari, Sahih, #3757].
At the time of actual war, if the leader of the army in the battle field was the Khalifah, both the flag (liwaa') and the banner (raya) can be lifted. It was reported in the seerah of Ibn Hisham during the talk about the ghazwah of great Badr that the flag and banner were present in the battle.
However, at time of peace or after the end of the battle the banners are usually spread amongst the army and lifted by its divisions, regiments, units and battalions, as narrated in the hadith of Al-Harith ibn Hassan Al-Bakri that talked about the army of Amru ibn Al-'As.
The Khalifah is the leader of the army in Islam
The Khalifah is the leader of the army in Islam. Therefore the flag is legally lifted on top of his headquarters, i.e. on top of the Khalifah's house. This is because the flag is tied to the amir of the army. The banner is allowed to be lifted on top of the Khalifah's house from an administrative point of view, taking into account the fact that the Khalifah is the head of the organisations of the State. In regards to the remaining organisations, departments and establishments of the State, the banner alone is lifted on top of them, because the flag is specific to the leader of the army as a mark to his location.
How the flag is tied
The flag is tied at the end of the spear and twisted around it. It is given to the leader of the army in accordance to the number of armies. Thus it is tied to the leader of the first army, the second army, or the leader of Al-Sham army, and Iraq army, or the leader of Aleppo army, or the leader of Beirut army, and so on.
In origin it is twisted at the end of the spear and not spread out except at the time of need. It is for example spread out on top of the Khalifah's house because of its importance. This applies also to the sites of the leaders of the armies at time of peace so that the Ummah can see the greatness of the flags of their armies. However, if this need conflicts with security issues, such as the enemy recognising the sites of the leaders of the armies, then the flag will be treated as in origin, i.e. it is not spread out but rather remains twisted/rounded.
In regards to the banner it is left for the wind to flap it, like the flags in use today. Therefore it is placed on top of the departments of the State.
Firstly: Regarding the army:
1. In case of actual war, the flag remains attached to the site of the leader of the army. In origin it must not be spread out, rather kept rounded/twisted around the spear. It can be spread out after studying the security issue. There will be a banner carried by the leader of the battle in the battle field. In case the Khalifah was in the battle field the flag is also allowed to be carried.
2. In case of peace the flag is tied to the leaders of the armies, and it is rounded at the spear; but it can be spread out on top of the sites of the leaders of the armies. Banners are usually spread out amongst the army carried by its divisions, units, regiments and battalions. It is possible for each division, a regiment, or a battalion to have a specific banner that distinguishes it administratively and which is lifted with the banner.
Secondly: Regarding the security organisations, departments, and establishments of the State, only the banner is lifted on top of each of them except the house of the Khilafah, where the flag is lifted on top of it as the Khalifah is the leader of the army. The banner is allowed to be lifted administratively together with it, because the house of the Khilafah is the head of the organisations of the State. The private establishments and ordinary people can also carry and lift the banner on top of their establishments, offices and houses, particularly on the occasions of eid, victories and the like.