This verse gives the reason for the previous exhortation. It is a pleasant thing if thou keep them within thee; in thy mind and memory (comp. Proverbs 18:8; Proverbs 20:27). Thus Psalms 147:1, "It is good to sing praises unto our God; for it is pleasant, and praise is comely."
They shall withal be fitted in thy lips. This rendering hardly suits the hortatory nature of the introduction. It is better to take the clause in the optative, as Delitzsch, Ewald, Nowack, and ethers: "Let them abide altogether upon thy lips;" i.
e. be not ashamed to profess them openly, let them regulate thy words, teach thee wisdom and discretion. Septuagint, "And if thou admit them to thy heart, they shall likewise gladden thee on thy lips."