Oneness of Allah, also known as Tawheed, is a fundamental concept in Islam that emphasises the belief in the unity of God within himself and uniqueness of Allah (God) from his creation. It is the core principle of Islamic monotheism, affirming that Allah is the only deity worthy of worship. Tawheed encompasses the following aspects:

Oneness of Lordship (Tawheed al-Rububiyyah):

This aspect of Tawheed acknowledges that Allah is the only one who creates, sustains, maintains, and controls the universe. It emphasises that Allah alone has the power to change the state of affairs and regulate everything in the universe. The Quran states, "Indeed, your Lord is Allah, who created the heavens and the earth in six days and then established Himself above the Throne" (Surah Yunus, 10:3).

Oneness of Names and Attributes (Tawheed al-Asma was-Sifat):

This aspect of Tawheed involves the acceptance and belief that all the most beautiful names and the most perfect attributes belong to Allah alone. It also implies that no created being can share in these divine names and attributes in their perfection and totality. For example, while humans can possess wisdom, it's understood that only Allah's wisdom is absolute and perfect.

Oneness of Worship (Tawheed al-Uluhiyyah/Ibadah):

This aspect focuses on the singularity of worship that should be directed towards Allah alone. It asserts that any form of worship, whether it is prayer, dedication, fasting, supplication, seeking help in times of distress, or giving thanks in times of prosperity, must be exclusively dedicated to Allah.

References from the Quran:

The Quran, the holy book of Islam, provides numerous verses that affirm the concept of Tawheed. Here are a few references:

"Say, 'He is Allah, [who is] One, Allah, the Eternal Refuge. He neither begets nor is born, nor is there to Him any equivalent'" (Surah Al-Ikhlas, 112:1-4). This verse emphasises the oneness and uniqueness of Allah.  "And your god is one God. There is no deity [worthy of worship] except Him, the Entirely Merciful, the Especially Merciful" (Surah Al-Baqarah, 2:163). This verse reinforces the belief in the oneness of Allah as the sole object of worship.

References from Hadith:

Narrated by ibn abbas: When the Prophet sent Muadh to Yemen, he said to him, "You are going to a nation from the people of the Scripture, so let the first thing to which you will invite them, be the Tauhid of Allah. If they learn that, tell them that Allah has enjoined on them, five prayers to be offered in one day and one night.

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Narrated Mu'adh bin Jabal: The Prophet said, "O Mu'adh! Do you know what Allah's Right upon His slaves is?" I said, "Allah and His Apostle know best." The Prophet said, "To worship Him (Allah) Alone and to join none in worship with Him (Allah). Do you know what their right upon Him is?" I replied, "Allah and His Apostle know best." The Prophet said, "Not to punish them (if they do so)."

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Narrated Abu Said Al-Khudri: A man heard another man reciting (in the prayers): 'Say (O Muhammad): "He is Allah, the One." (112.1) And he recited it repeatedly. When it was morning, he went to the Prophet and informed him about that as if he considered that the recitation of that Sura by itself was not enough. Allah's Apostle said, "By Him in Whose Hand my life is, it is equal to one-third of the Quran."

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Narrated 'Aisha: The Prophet sent (an army unit) under the command of a man who used to lead his companions in the prayers and would finish his recitation with (the Sura 112): 'Say (O Muhammad): "He is Allah, the One." ' (112.1) When they returned (from the battle), they mentioned that to the Prophet. He said (to them), "Ask him why he does so." They asked him and he said, "I do so because it mentions the qualities of the Beneficent and I love to recite it (in my prayer)." The Prophet; said (to them), "Tell him that Allah loves him"

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Importance of Tawheed in Islam:

Tawheed holds great importance in Islamic belief and practice. It is without doubt the most fundamental belief in islam and without it one cannot be regarded as a muslim. Here are a few more reasons why Tawheed is crucial in Islam:

Monotheism: Tawheed promotes pure monotheism, ensuring that Muslims worship Allah alone and refrain from associating partners with Him. This belief guards against polytheism and idolatry, which are considered major sins in Islam.

Spiritual Connection: Tawheed establishes a deep spiritual connection between Muslims and Allah. By recognizing Allah's oneness, Muslims develop a profound sense of devotion, reliance, and gratitude towards their Creator.

Ethical Guidance: Tawheed serves as a moral compass, guiding Muslims in their ethical conduct. Belief in the oneness of Allah encourages Muslims to lead righteous lives, uphold justice, show kindness, and fulfil their responsibilities towards others.

Unity and Brotherhood: Tawheed fosters unity and brotherhood among Muslims. It emphasises the equality and mutual respect of all believers, transcending boundaries of race, ethnicity, and social status.

In summary, Tawheed is a central concept in Islam that emphasises the oneness and uniqueness of Allah. It encompasses the belief in worshipping Allah alone and recognizing His sovereignty over the universe. The Quran and Hadith provide references that affirm the importance of Tawheed in Islamic belief and practice. By adhering to Tawheed, Muslims affirm their belief in the absolute oneness of Allah and strive to lead lives in accordance with His guidance and commandments.