Muhammed al Massari, in his book “Kitab-at-Tawheed” explains the meaning of worship, where he makes mention of this important point:
“The conception of “worship” has an objective reality, and it was indeed realized intellectually, before revealing the divine laws, otherwise sayings of the prophets; “You must worship none except Allah”, is nonsense, because the people would say what does “worship” mean? We do not know its meaning. But the perception reality, historical recurrence and the absolute texts of the Glorious Qur’ân clarify that they understood what the Prophets said instantly. In fact, a lot of them hurried to deny and argue;
“And we are not going to be forsaker of our deities on your saying.” (Hûd, 11:53) He also says, “What! Has he made the deities into a single God? This is in truth a wonderful thing!” (Sâd, 38:5)
So the people understood the sayings of the Prophets (peace be upon all them) instantly, knowing that it was the great calamity, the absolute opposition and the complete destructive for their inherited beliefs, because it called for their gods nullity, asserting that these gods are mere fables and have no way to the truth. What was the conception of “worship” or “God” which the Prophets and their peoples disputed? What was the relation between the two conceptions?” End Quote
Therefore, the essential and fundamental meaning of worship and illaah is universal and not something a polytheist was ignorant of prior to revelation or something that undergoes abrogation with time and place or something that has to do with outward rituals. Beware of those definitions that insert only the non-essential extended meanings and non-essential outward forms or makes use of mere examples for defining “ilaah”, “ibaadah” or “tawheed”; and using which they then declare Muslims as polytheists.