As Salam 'Alaykom, Tauhid is divided into three categories, Ar Rabubiyyah, Al Uluhiyyah and Asma was Sifat. When was Tauhid first categorized and who were the scholars that did it? Jazak'Allahu Khair.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

Dr. Bakr Abu Zayd stated that this categorization was referred to by At-Tabari and Ibn Mandah and he stated that Shaykh Al-Islam Ibn Taymiyyah and Ibn al-Qayyim stated it in their books. It was also stated by as Az-Zabeedi in Taaj Al-‘Aroos and Shaykh Ash-Shinqeeti in Adhwaa’ Al-Bayaan.

Shaykh Bakr said: "This inductive categorization among the earlier scholars of the Salaf (righteous predecessors) was mentioned by Ibn Mandah, Ibn Jareer At-Tabari and others, and this was stated by Shaykh Al-Islam Ibn Taymiyyah and Ibn al-Qayyim; and it was stated by Az-Zabeedi in Taaj Al-‘Aroos, Shaykh Ash-Shinqeeti in Adhwaa’ Al-Bayaan and others all. It consists of an induced conclusion from an exhaustive study of the religious texts, and this is consistent among the people of every discipline, as with the grammaticians, who induced that the words of the Arabs are categorized into noun, verb and particle, although the Arabs did not mention this; yet no one criticized the grammaticians for it, and the same will be said about all other instances of inductive reasoning." [End of quote]

Shaykh Abdur-Raheem As-Sulami mentioned in his book entitled At-Tawheed Bayna-l-Mutakallimeen wa Ahl As-Sunnah that some scholars of the Salaf stated this categorization before Shaykh Al-Islam Ibn Taymiyyah .

This categorization is induced from the texts of the Quran and the Sunnah as stated by Shaykh Bakr Abu Zayd just as the scholars induced from an exhaustive study of the texts of the Quran and Sunnah concerning the prayer that it consists of conditions; and they mentioned their number and categorized them into conditions of validity and conditions of obligation; and they also induced that it consists of acts without which the prayer is invalid, and which are not compensated by Sujood As-Sahw (prostration of forgetfulness), so they named them Pillars and mentioned their number. They did the same in regard to Wudhoo’ (ablution) and all other acts of worship. Similarly, they exhaustively studied the texts of the Quran and the Sunnah and found that Allaah commands us to assert the oneness of His Ruboobiyyah (Lordship), Uloohiyyah (Worship), and Asmaa’ wa-Sifaat (Names and Attributes).

For more benefit, please refer to Fatwa 16146.

Allaah Knows best.