9. For what thanks—what sufficient thanks?
render … again—in return for His goodness (Ps 116:12).
for you—"concerning you."
for all the joy—on account of all the joy. It was "comfort," 1Th 3:7, now it is more, namely, joy.
for your sakes—on your account.
before our God—It is a joy which will bear God's searching eye: a joy as in the presence of God, not self-seeking, but disinterested, sincere, and spiritual (compare 1Th 2:20; Joh 15:11).