'Instruction' in the Bible

He must hold firmly to the trustworthy word [of God] as it was taught to him, so that he will be able both to give accurate instruction in sound [reliable, error-free] doctrine and to refute those who contradict [it by explaining their error].

But you, speak [the things] which are fitting for sound instruction.

sound and beyond reproach in instruction, so that the opponent [of the faith] will be shamed, having nothing bad to say about us.