A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
psa 65:1This is a song of praise for God's spiritual blessings to His people and His kind providence over all the earth. (Psa 65:1-13)
Praise waiteth for thee--literally, "To Thee silence praise," or (compare Psa 62:1), To Thee silence is praise--that is, Praise is waiting as a servant; it is due to Thee. So the last clause expresses the duty of paying vows. These two parts of acceptable worship, mentioned in Psa 50:14, are rendered in Zion, where God chiefly displays His mercy and receives homage.
psa 65:2All are encouraged to pray by God's readiness to hear.
psa 65:3God's mercy alone delivers us from the burden of iniquities, by purging or expiating by an atonement the transgressions with which we are charged, and which are denoted by--
Iniquities--or, literally, "Words of iniquities."
psa 65:4dwell in thy courts; . . . [and] satisfied with the goodness . . . temple--denote communion with God (Psa 15:1; Psa 23:6; compare Psa 5:7). This is a blessing for all God's people, as denoted by the change of number.
psa 65:5terrible things--that is, by the manifestation of justice and wrath to enemies, accompanying that of mercy to His people (Psa 63:9-11; Psa 64:7-9).
the confidence--object of it.
of all . . . earth--the whole world; that is, deservedly such, whether men think so or not.
psa 65:6God's great power and goodness are the grounds of this confidence. These are illustrated in His control of the mightiest agencies of nature and nations affecting men with awe and dread (Psa 26:7; Psa 98:1, &c.), and in His fertilizing showers, causing the earth to produce abundantly for man and beast.
psa 65:8outgoings of . . . rejoice--all people from east to west.
psa 65:9visitest--in mercy (compare Psa 8:4).
river of God--His exhaustless resources.
psa 65:11thy paths--ways of providence (Psa 25:4, Psa 25:10).
psa 65:12wilderness--places, though not inhabited by men, fit for pasture (Lev 16:21-22; Job 24:5).
pastures--is literally, "folds," or "enclosures for flocks"; and in Psa 65:13 it may be "lambs," the same word used and so translated in Psa 37:20; so that "the flocks are clothed with lambs" (a figure for abundant increase) would be the form of expression.