Not giving heed to Jewish fables, and commandments of men, that turn from the truth. Not giving heed to - namely, "they" (Titus 1:13).
Jewish fables (notes, 1 Timothy 1:4; 1 Timothy 4:7; 2 Timothy 4:4). These formed the transition to subsequent Gnosticism; as yet the error was but profitless, not tending to godliness, rather than openly opposed to the faith. Commandments of men - as to ascetic abstinence (Titus 1:15; Mark 7:7-9; Colossians 2:16; Colossians 2:20-23; 1 Timothy 4:3); here resting not on the law, but on men's invention.
That turn from the truth - whose characteristic is this (2 Timothy 4:4).