“Who loves life, that is, whoever transforms himself for true life and wishes to show it as worthy of love. For this is indicated by the expression ‘who loves,’ as though to show it desirable to people to the point of rivalry. Let him unfailingly hold to what the prophetic word also proposes together with me” (Theophylact).
“To see” means to experience, to enjoy; cf. 1 Jn 3:2. Such a happy life is a gift of God’s mercy. Yet man, for his part, must use whatever means are possible for him to attain this high aim of life.
The effective means indicated by the Psalmist, and by the Apostle from his words, are these: restraining the tongue from evil and deceitful speech, that is, bridling the tongue. The Apostle James depicts this with such force (Jas 3:2 and following). The expression indicates the tongue’s natural lack of restraint and its stubborn inclination toward evil.