A.T. Robertson Commentary Romans 15:18

"For I will not dare to speak of any things save those which Christ wrought through me, for the obedience of the Gentiles, by word and deed," — Romans 15:18 (ASV)

Any things save those which Christ wrought through me (τ ων ου κατειργασατο Χριστος δι' εμου). Rather, "any one of those things which Christ did not work through me." The antecedent of ων is the unexpressed τουτων and the accusative relative α (object of κατειργασατο) is attracted into the genitive case of τουτων after a common idiom.

By word and deed (λογω κα εργω). Instrumental case with both words. By preaching and life (Luke 24:19; Acts 1:1; Acts 7:22; 2 Corinthians 10:11).