John Gill Bible Commentary

Let my mouth be filled with thy praise,.... Or "thy praise shall fill my mouth" (x); which shows that his heart was affected with the goodness of God to him, and that he had a deep impression and sense of it upon him; for out of the abundance of the heart the mouth speaks; and for the mouth to be filled with the praise of God, is to speak largely, publicly, and with great delight, in the praise of God, his divine perfections and benefits; and with thy honour all the day; the excellency of his nature, the glory of his majesty, the honour due unto him, on account of his being, attributes, and blessings of providence and grace; a work to be employed in all the day, evening, morning, and at noon; as often as prayer is made to God, praise, honour, and glory, should be given him; since his mercies are new every morning, and they continue all the day long; his goodness endures for ever. (x)