Let the words of my mouth, and the meditation of my heart, be acceptable in thy sight, O LORD, my strength, and my redeemer.
Let the words of my mouth - Let the prayer which is the main object of this psalm, as well as the praises which form the introduction to the prayer, find acceptance with thee. The Hebrew х lªraatsown (H7522)] for "be acceptable" is literally, 'be for pleasure' to thee. Hengstenberg suggests that David uses a sacrificial term; perhaps the very words which were spoken by the priests at the presentation of the sacrifice (cf. Leviticus 19:5; Leviticus 19:7; Isaiah 56:7). Sacrifice itself is the embodiment of prayer. Hence, the metaphor is natural (Romans 12:1).
O Lord, my strength - literally, my rock (Psalms 18:2), denoting His immovable faithfulness to His promises.