Surah 17. Al-Israa, Ayah 56

As the sequence shows, this relates to the worship of saints or angels.

I.e., to transfer it unto themselves: obviously an allusion to the Christian doctrine of "vicarious atonement".

Sc., "to those who believe in the existence of any divine power apart from God".

 i.e., Jesus, Ezra, and the angels. Idol worship is refuted in other passages such as 7:191-198 and 34:22.

Men's suspicions of each or of the prophets have been condemned in the previous verses. We now have the strongest condemnation of all, that of imagining any other being as being equal or in the same category with One true God. Allah has all power: they have no power. They cannot remove men's troubles. They cannot even mitigate or change them so as to afford the least relief. Why indulge in false worship?