Tafsir of Al-Anbiya' 21:50

{And this is a blessed reminder} It is the Qur’an. Its blessing lies in the abundance of its benefits and the profusion of its goodness.

{And We had certainly given Abraham his guidance before, and We were of him well-knowing.} Meaning: We gave him the ability to distinguish truth from falsehood, and the maturity of intellect, before he reached the age of prophethood. {And We were of him well-knowing} means: We knew he was worthy of the Message and fit for the mission.

{When he said to his father and his people, "What are these statues to which you are devoted?"} He asked them this by way of rebuke and invalidation of their worship.

{They said, "We found our fathers worshippers of them."} They relied upon the imitation of their ancestors as their only proof.

{He said, "You have certainly been, you and your fathers, in clear error."} He declared that both they and their ancestors were in manifest misguidance, for imitation is not a valid basis for truth.