The central verse is arguably 126:
How does God act?
Cassiodorus suggests that the answer is by sending us the Saviour:
“It is time to do, in other words, time to appear as Saviour to the world, to loosen sins, to conquer death, and to lay low the devil with his troop. This is what the Lord's doing is, to come at the prophesied time. In the words of the prophet: In an acceptable time I have heard thee, and in the day of salvation I have helped thee; and as Paul says: Behold, now is the acceptable time; behold, now is the day of salvation.”
Whether you see this salvation primarily in terms of the Incarnation, Cross, Resurrection or Second Coming, I think, depends on your particular spirituality. In verse 123, the psalmist says that he faints after [the desire of] God’s salvation, which St Augustine sees as the Cross, prefigured by Moses’ holding aloft the image of a serpent on a pole. But Cassiodorus points to the Incarnation.
Acting through us
But there is an alternative interpretation to the Latin of verse 126 (albeit one corrected in the neo-Vulgate) as Haydock’s classic commentary points out: the Latin could be read as suggesting that it is time for us to act for the Lord, ‘by striving to repair the injuries done to his name and worship’.
Textual ambiguities aside (on which you can read more over at my post on this stanza on Psallam Domino blog if you are interested) it is a useful reminder that God acts in history through us: we cannot just sit back and wait for the Second Coming, we must do what we are called to do in the world here and now.
Of course action for Christ calls forth reaction, and the stanza also serves to remind us of the ‘almost but not yet’ dimension of salvation: even though the Messiah has come, as we celebrate this coming Easter, we must still beg God daily, with the psalmist, for protection against those who slander us here and now (verses 121-122); for knowledge, understanding and the grace to do God’s will (verses 124-125); and above all for mercy rather than judgment on our sins when it comes to our end (verse 124).
121 Feci judicium et justitiam : non tradas me calumniantibus me.
I have done judgment and justice: give me not up to them that slander me
122 Suscipe servum tuum in bonum : non calumnientur me superbi.
Uphold your servant unto good: let not the proud calumniate me.
123 Oculi mei defecerunt in salutare tuum, et in eloquium justitiæ tuæ.
My eyes have fainted after your salvation: and for the word of your justice
124 Fac cum servo tuo secundum misericordiam tuam, et justificationes tuas doce me.
Deal with your servant according to your mercy: and teach me your justifications.
125 Servus tuus sum ego: da mihi intellectum, ut sciam testimonia tua.
I am your servant: give me understanding that I may know your testimonies.
126 Tempus faciendi, Domine : dissipaverunt legem tuam.
It is time, O Lord, to do: they have dissipated your law.
127 Ideo dilexi mandata tua super aurum et topazion.
Therefore have I loved your commandments above gold and the topaz.
128 Propterea ad omnia mandata tua dirigebar; omnem viam iniquam odio habui.
Therefore was I directed to all your commandments: I have hated all wicked ways.