As-Salaam alaikum,
All said and done, from whatever perspective you look at it, TAWHID is contained in 4 Phrases as follows:--

ALHAMDULILLAH

LA ILAHA ILLALLAH

ALLAHU AKBAR

LA HAWLA WA LAA QUWATA ILLA BILLAH.

Taken together, these 4 phrases encompass Tawhid (Worshipping Allah alone) and QADR (Pre-decree).

Ibn Abi Awfaa, may Allah be pleased with him, said, a man came to the Prophet, Sallallahu alaihi Wasallam, and said: "I cannot learn the Qur'an, so teach me something that will suffice me. He said, [recite] SUBHAANALLAH, WALHAMDULILLAH, WA LAA ILAHA ILLALLAH, WALLAHU AKBAR, WALA HAULA WALAA QUWATA ILLA BILLAAH.." [Abu Dawud 832, Nisa'i 2/143].

Abu Hurairah, may Allah be pleasedf with him, reported: "Shall I inform you of a phrase which is under the throne and from amongst the treasures of paradise? Say, LA HAULA WALA QUWATA ILLA BILLAH. Allah will say, 'My Servant has submitted himself in intention, action and worship (aslama was-taslama)." [Hakim, Darabi, Fath al-Bari 11/501].

A servant does not control any of his affairs; he does not have the means to repel harm or the ability to attain goodness except by Allah's Will. A servant cannot change disobedience to obedience, sickness to health, weakness to strength, deficiency to perfection except by Allah's Help.

What Allah Wills happens and what He does not Will won't happen. The affairs of creation are tied to His Decree and Pre-Destination, Tabaraka Wa Ta'ala.