“Surely there is a Sign in this, but most of them would not believe. Verily your Lord is Immensely Mighty, Ever Compassionate.” (Al Qur’ān – 26:103-104)
The “sign” in the story of Prophet Abraham has two aspects: the unbelievers of Makkah and especially the Quraysh claimed to be the followers of Abraham and were proud of being his descendants. In actual fact, however, they were immersed in shirk (associating others with God in His Divinity) against which Abraham had fought all his life. Further, as far as the Prophet Muhammad (peace and blessings of Allah be to him) was concerned – he who had brought to them the same religion that Abraham had preached – they treated him in exactly the same manner as Abraham’s people had treated him.
The Quraysh are being reminded, in this context, that Abraham was a standard-bearer of tawḥīd (affirmation that God is One and that He Alone should be served) and was an enemy of shirk, and that they themselves admitted that he was not a polytheist. Nevertheless, they did not pay heed to the call of the Truth.
The second aspect of “sign” in this story is that Abraham’s nation was obliterated from the face of the earth in such a way that not even a trace of it has remained. If any of that nation had survived, they were Abraham and his sons, Isaac and Ishmael.
Although the Qur’ān does not explicitly mention the punishment which befell Abraham’s nation, they are included among those who were struck by God’s Wrath as we find in Surah al-Tawbah 9:70.