Wherewith shall a young man cleanse his way? By taking heed thereto according to thy word.
Wherewithal shall a young man cleanse his way? By taking heed thereto according to thy word.
How shall a young man cleanse his way? By taking heed and keeping watch [on himself] according to Your word [conforming his life to it].
How can young people keep their paths pure? By guarding them according to what you’ve said.