التفسير التبليغي
(أَجَعَلَ الْآلِهَةَ إِلَٰهًا وَاحِدًا إِنَّ هَٰذَا لَشَيْءٌ عُجَابٌ) (5)
They were astonished by his call to them to worship the One God.
(إِنَّ هَٰذَا), meaning this monotheism (Tawhid) to which you invite us, (لَشَيْءٌ عُجَابٌ) is indeed a most astonishing thing.
They are astonished by the pure call to monotheism because it poses a threat to them.
The people of the pre-Islamic era (Jahiliyyah) used to believe that their needs were met through idols, so they were astonished and said: (أَجَعَلَ الْآلِهَةَ إِلَٰهًا وَاحِدًا إِنَّ هَٰذَا لَشَيْءٌ عُجَابٌ).
They are making others believe that there is a hidden agenda behind this call, something other than what appears.
The Quran portrays the extent of their astonishment.
(إِنَّ هَٰذَا لَشَيْءٌ عُجَابٌ), and that is because it contradicts what they found their forefathers accustomed to.
Sa'id ibn Jubayr narrated: Abu Talib fell ill, so the Prophet (peace be upon him) came to visit him. There was a space for a man at his head, so Abu Jahl stood up and sat there. They complained about the Prophet (peace be upon him) to Abu Talib, saying: "Indeed, he speaks ill of our gods." So Abu Talib said: "O son of my brother, what do you want from these people?" He (the Prophet) said: "O uncle, I want them to accept a word by which the Arabs will submit to them, and the non-Arabs will pay them tribute." He asked: "And what is it?" He said: "There is no god but Allah (La ilaha illallah)." So they said: (أَجَعَلَ الْآلِهَةَ إِلَٰهًا وَاحِدًا إِنَّ هَٰذَا لَشَيْءٌ عُجَابٌ).
Source: التفسير التبليغي