In The Name of Allaah, The Most Merciful, The Bestower of Allaah.
Many people humble themselves to one another more than they humble themselves to Allaah – The Most High, The Most Great. It is neither permissible for a person to be a slave [i.e. by worshipping anyone] except to Allaah, nor humble himself except to the Greatness of Allaah. Allaah [Glorified be He and free is He from all imperfections] said:
هُوَ ٱللَّهُ ٱلَّذِى لَآ إِلَـٰهَ إِلَّا هُوَۖ عَـٰلِمُ ٱلۡغَيۡبِ وَٱلشَّهَـٰدَةِۖ هُوَ ٱلرَّحۡمَـٰنُ ٱلرَّحِيمُ
هُوَ ٱللَّهُ ٱلَّذِى لَآ إِلَـٰهَ إِلَّا هُوَ ٱلۡمَلِكُ ٱلۡقُدُّوسُ ٱلسَّلَـٰمُ ٱلۡمُؤۡمِنُ ٱلۡمُهَيۡمِنُ ٱلۡعَزِيزُ ٱلۡجَبَّارُ ٱلۡمُتَڪَبِّرُۚ سُبۡحَـٰنَ ٱللَّهِ عَمَّا يُشۡرِڪُونَ
هُوَ ٱللَّهُ ٱلۡخَـٰلِقُ ٱلۡبَارِئُ ٱلۡمُصَوِّرُۖ لَهُ ٱلۡأَسۡمَآءُ ٱلۡحُسۡنَىٰۚ يُسَبِّحُ لَهُ ۥ مَا فِى ٱلسَّمَـٰوَٲتِ وَٱلۡأَرۡضِۖ وَهُوَ ٱلۡعَزِيزُ ٱلۡحَكِيمُ
He is Allaah than Whom there is none who has the right to be worshipped but He; the King, the Holy, the One Free from all defects, the Giver of security, the Watcher over His creatures, the All-Mighty, the Compeller, the Supreme. Glory be to Allaah! [High is He] above all that they associate as partners with Him. He is Allaah, the Creator, the Inventor of all things, the Bestower of forms. To Him belong the Best Names. All that is in the heavens and the earth glorify Him. And He is the All-Mighty, the All-Wise. [Surah Al-Hashar’ Aayaat 23-24]
Examine those Aayaat in the last part of Surah Al-Hashar! The statement: [هُوَ ٱللَّهُ ٱلَّذِى لَآ إِلَـٰهَ إِلَّا هُوَ – He is Allah than Whom there is none who has the right to be worshipped but He)]: This necessitates Tawheed Al-Uloohiyyah.
The statement: [هُوَ ٱللَّهُ ٱلَّذِى لَآ إِلَـٰهَ إِلَّا هُوَۖ عَـٰلِمُ ٱلۡغَيۡبِ وَٱلشَّهَـٰدَةِۖ هُوَ ٱلرَّحۡمَـٰنُ ٱلرَّحِيمُ- He is Allaah, than Whom there is none who has the right to be worshipped but He, the All-Knower of the unseen and the seen (open). He is the Most Beneficent, the Most Merciful]: This necessitates Tawheed Al-Asmaa Was Sifaat.
And the statement: [هُوَ ٱللَّهُ ٱلۡخَـٰلِقُ ٱلۡبَارِئُ ٱلۡمُصَوِّرُۖ – He is Allaah, the Creator, the Inventor of all things, the Bestower of forms” necessitates Tawheed Ar-Roboobiyyah].
These few Aayaat in the last part of Surah Al-Hashr necessitate all the categories of Tawheed.
Majmoo’ah Wa Rasaail Wa Fataawa 1/22 (excerpt and abridged)