Here is the mp3 from JoguesChant, and here is the score from the Brazilian Benedictines:
The text is a famous one, from Psalm 130; in the Introit, verse 2 and the first half of verse 3 of the Psalm comes first, and verse 1 follows:
Out of the depths have I called to you, O LORD;
LORD, hear my voice; *
let your ears consider well the voice of my supplication.
If you, LORD, were to note what is done amiss, *
O Lord, who could stand?
For there is forgiveness with you; *
therefore you shall be feared.
I wait for the LORD; my soul waits for him; *
in his word is my hope.
My soul waits for the LORD,
more than watchmen for the morning, *
more than watchmen for the morning.
O Israel, wait for the LORD, *
for with the LORD there is mercy;
With him there is plenteous redemption, *
and he shall redeem Israel from all their sins.
Here's a polyphonic version written by Samuel Wesley, and sung by the Scuola Corale della Cattedrale in Lugano:
This Psalm has been an option in the Burial Rite since the 1928 Book of Common Prayer in the U.S.; here's a gorgeous version of the haunting De Profundis ("Out of the Deep") from John Rutter's Requiem, sung by Monteverdi Choir Würzburg:
That piece uses the Coverdale translation of the Psalm, of course:
1 Out of the deep have I called unto thee, O Lord *
Lord, hear my voice.
2 O let thine ears consider well *
the voice of my complaint.
3 If thou, Lord, wilt be extreme to mark what is done amiss *
O Lord, who may abide it?
4 For there is mercy with thee *
therefore shalt thou be feared.
5 I look for the Lord; my soul doth wait for him *
in his word is my trust.
6 My soul fleeth unto the Lord *
before the morning watch, I say, before the morning watch.
7 O Israel, trust in the Lord, for with the Lord there is mercy *
and with him is plenteous redemption.
8 And he shall redeem Israel *
from all his sins.
And here's Arvo Pärt's De Profundis, evidently sung by the Hilliard Ensemble:
I'm quite a huge fan of Arvo Pärt, I always note with surprise.
In any case, this is another of the very powerful "Crying Psalms," used by composers to express deep mourning or anguish of the soul. I am interested in its use here in October as the Introit, and made a little Google search on the topic. In doing this, I came across a book titled "The Advent project: the later-seventh-century creation of the Roman Mass proper," which I had in my Google library, but hadn't looked at yet. While I'm not sure why "Si Iniquitates" is here, I did learn that the post-Pentecost Introits start out with 16 Psalm texts - and these particular Psalms are all in numerical order. Then follow texts from a variety of sources, one of which is this Psalm. I also learned that "the most noteworthy feature of the sequence as a whole is that it comprises a set of twenty-two uniquely assigned chants (indeed twenty-five including those of the Ember Days), a further testimony to the extraordinary completeness of the introit's annual cycle."
While this isn't an answer to my particular question, it's pretty fascinating, and here's the section I'm talking about, embedded:
The Collect of the Day is this one:
Lord, we pray that your grace may always precede and follow us, that we may continually be given to good works; through Jesus Christ our Lord, who lives and reigns with you and the Holy Spirit, one God, now and for ever. Amen.
Quite lovely, and much shorter than many. Again I wish I had the Hatchett commentary at hand to see where this one came from; perhaps Caelius will help us out. (EDIT: Yes, indeed he did. Here's the good stuff, from his comments:
Hackett on the Collect for Proper 23,
"This appears in the Gregorian sacramentary among a group of prayers for morning and evening (no. 966) ad in the supplement (no. 1177) as the collect for the seventeenth Sunday after (the) Pentecost (octave). It is used for the seventeenth Sunday after Trinity in the Sarum missal and earlier Prayer Books. "All" is not in the Latin. Earlier editions had "prevent" in [one of] its archaic meaning[s] "go before" (rather than its modern meaning "hinder"). The prayer is for grace which anticipates us as well as grace which accompanies us that we may be continually dedicated to good works--"prevenient" [usually attributed to John Wesley] and "cooperating" grace.
Along with a note that "The comments in brackets are mine. I just find it funny that Wesley had to remind people of concepts already apparent in shorthand in the ancient Collects." Thanks again, Caelius.)
Here is De Profundis from the Très Riches Heures du Duc de Berry: