Teach me thy way, O Lord (comp. Psalms 25:3, and the comment ad loc.). And lead me in a plain path; literally, a level path—a path traversing a fiat and smooth country, not one where the ground is rugged and beset with rocks and precipices.
Because of mine enemies. David's enemies are ever at hand, to swallow him up (Psalms 56:2). If his way be not plain and smooth, it will be to their advantage and to his detriment.