A Matins Invitatory for Trinity: Deum verum

Sung by Psallentes, a great Belgian chant group:



Below is the full text of the Matins Invitatory, from Breviary.net.  [EDIT:  That site requires registration and asks for a subscription fee now, but Divinum Officium will give you the text for Trinity Matins; just enter 5-26-2013 for this year's date of Trinity Sunday.]

Deum verum, unum in Trinitáte, et Trinitátem in Unitáte, * Veníte, adorémus.	Very God, One in Trinity, and Trinity in Unity, * O come, let us worship.
Deum verum, unum in Trinitáte, et Trinitátem in Unitáte, * Veníte, adorémus.	Very God, One in Trinity, and Trinity in Unity, * O come, let us worship.
Psalmus 94. Venite, exsultemus Domino	Psalm 94. Venite, exsultemus Domino
Veníte, exsultémus Dómino, jubilémus Deo, salutári nostro : præoccupémus fáciem ejus in confessióne, et in psalmis jubilémus ei.	O come, let us sing unto the Lord ; let us heartily rejoice in the God of our salvation.  Let us come before his presence with thanksgiving ; and shew ourselves glad in him with psalms.
Deum verum, unum in Trinitáte, et Trinitátem in Unitáte, * Veníte, adorémus.	Very God, One in Trinity, and Trinity in Unity, * O come, let us worship.
Quóniam Deus magnus Dóminus, et Rex magnus super omnes deos : quóniam non repéllet Dóminus plebem suam : quia in manu ejus sunt omnes fines terræ, et altitúdines móntium ipse cónspicit.	For the Lord is a great God ; and a great King above all gods:  For the Lord will not cast off his people:  In his hand are all the corners of the earth, and the strength of the hills is his also.
Veníte, adorémus.	O come, let us worship.
In the following verse of the Psalm, at the words veníte, adorémus, et procidámus ante Deum (O come, let us worship and fall down, and kneel before the Lord our Maker) all genuflect.
Quóniam ipsíus est mare, et ipse fecit illud, et áridam fundavérunt manus ejus : veníte, adorémus, et procidámus ante Deum : plorémus coram Dómino, qui fecit nos, quia ipse est Dóminus Deus noster ; nos autem pópulus ejus, et oves páscuæ ejus.	The sea is his and he made it ; and his hands prepared the dry land.  O come, let us worship and fall down, and kneel before the Lord our Maker: For he is the Lord our God ; and we are his people, and the sheep of his pasture.
Deum verum, unum in Trinitáte, et Trinitátem in Unitáte, * Veníte, adorémus.	Very God, One in Trinity, and Trinity in Unity, * O come, let us worship.
Hódie, si vocem ejus audiéritis, nolíte obduráre corda vestra, sicut in exacerbatióne, secúndum diem tentatiónis in desérto : ubi tentavérunt me patres vestri, probavérunt et vidérunt ópera mea.	Today if ye will hear his voice, harden not your hearts, as in the provocation, and as in the day of temptation in the wilderness ; when your fathers tempted me, proved me, and saw my works.
Veníte, adorémus.	O come, let us worship.
Quadragínta annis próximus fui generatióni huic, et dixi : Semper hi errant corde ; ipsi vero non cognovérunt vias meas : quibus jurávi in ira mea : Si introíbunt in réquiem meam.	Forty years long was I grieved with this generation, and said, It is a people that do err in their hearts, for they have not known my ways:  unto whom I sware in my wrath, that they should not enter into my rest.
Deum verum, unum in Trinitáte, et Trinitátem in Unitáte, * Veníte, adorémus.	Very God, One in Trinity, and Trinity in Unity, * O come, let us worship.
Glória Patri, et Fílio, et Spirítui Sancto.  Sicut erat in princípio, et nunc, et semper,  et in sæcula sæculórum.  Amen.	Glory be to the Father, and to the Son, and to the Holy Ghost:  as it was in the beginning, is now, and ever shall be, world without end.  Amen.
Veníte, adorémus.	O come, let us worship.
Deum verum, unum in Trinitáte, et Trinitátem in Unitáte, * Veníte, adorémus.	Very God, One in Trinity, and Trinity in Unity, * O come, let us worship.
Hymnus Summæ Parens cleméntiæ, Mundi regis qui máchinam, Uníus et substántiæ, Trinúsque persónis Deus : Da déxteram surgéntibus, Exsúrgat et mens sóbria, Flagrans et in laudem Dei Grates repéndet débitas. Deo Patri sit glória, Natóque Patris único, Cum Spíritu Paráclito, In sempitérna sæcula.  Amen.	The Hymn O God of mercy passing thought, Who hast the world contrived and wrought ; In might, essential Unity, In Persons, blessed Trinity : Uplift us with thine arm of might, And let our hearts rise pure and bright, And, ardent in God's praises, pay The thanks we owe him every day. Glory to thee, O Father, Lord, And to thy Sole-begotten Word, Both with the Holy Spirit One While everlasting ages run.  Amen.
As soon as the introductory part of Matins is finished, there is begun The First Nocturn.  The Psalms with their Antiphons are those of the Common of the Blessed Virgin Mary, as given below.

The hymn listed above is not included on the video, and does not appear in  Hymn melodies for the whole year, from the Sarum service-books as one of the Sarum Trinity Office hymns (see this last link for the Sarum hymns).  TPL describes Summæ Parens cleméntiæ this way:

The author of this 7th century hymn is unknown. In the Roman Breviary this hymn is used at Saturday Matins during Ordinary Time. In the Liturgia Horarum the hymn is used on the first and third weeks of the Psalter for the Office of the Readings during Ordinary Time.

The Te Deum is sung at the end of Matins - and often at the Mass on the day, too.  Here's a Solemn Te Deum, sung by "Monks of the one of the Abbeys of the Solesmes Congregation," it says at the YouTube page.

Here's a post on the Te Deum.   And here is the Latin, and the English translation from the 1662 Book of Common Prayer:

Te Deum laudamus:
te Dominum confitemur.
Te aeternum Patrem
omnis terra veneratur.
Tibi omnes Angeli;
tibi caeli et universae Potestates;
Tibi Cherubim et Seraphim
incessabili voce proclamant:
Sanctus, Sanctus, Sanctus, Dominus
Deus Sabaoth.
Pleni sunt caeli et terra
maiestatis gloriae tuae.
Te gloriosus Apostolorum chorus,
Te Prophetarum laudabilis numerus,
Te Martyrum candidatus laudat exercitus.
Te per orbem terrarum
sancta confitetur Ecclesia,
Patrem immensae maiestatis:
Venerandum tuum verum et unicum Filium;
Sanctum quoque Paraclitum Spiritum.
Tu Rex gloriae, Christe.
Tu Patris sempiternus es Filius.
Tu ad liberandum suscepturus hominem,
non horruisti Virginis uterum.
Tu, devicto mortis aculeo, aperuisti
credentibus regna caelorum.
Tu ad dexteram Dei sedes, in gloria Patris.
Iudex crederis esse venturus.
Te ergo quaesumus, tuis famulis subveni:
quos pretioso sanguine redemisti.
Aeterna fac cum sanctis tuis in gloria numerari.
Salvum fac populum tuum,
Domine, et benedic hereditati tuae.
Et rege eos, et extolle illos usque in aeternum.
Per singulos dies benedicimus te;
Et laudamus Nomen tuum in saeculum, et in saeculum saeculi.
Dignare, Domine, die isto sine peccato nos custodire.
Miserere nostri domine, miserere nostri.
Fiat misericordia tua,
Domine, super nos, quemadmodum speravimus in te.
In te, Domine, speravi:
non confundar in aeternum.

We praise thee, O God
we acknowledge thee to be the Lord
All the earth doth worship thee
the Father everlasting.
To thee all the angels cry aloud
the heavens and all the powers therein.
To thee cherubim and seraphim do continually cry
Holy, Holy, Holy,
Lord God of Sabaoth; heaven and earth
are full of the majesty of thy glory.
The glorious company of apostles praise thee.
The goodly fellowship of the prophets praise thee.
The noble army of martyrs praise thee.
The Holy Church
throughout all the world doth acknowledge thee;
the father of an infinite majesty;
thine honourable true and only Son;
also the Holy Ghost the comforter.
Thou art the King of Glory, O Christ.
Thou art the everlasting Son of the Father.
When thou tookest upon thee to deliver man,
thou didst not abhor the Virgin's womb.
When thou hadst overcome the sharpness of death,
thou didst open the kingdom of heaven to all believers.
Thou sittest at the hand of God in glory of the Father.
We believe that Thou shalt come to be our Judge.
We therefore pray thee, help thy servants,
whom thou hast redeemed with thy precious blood.
Make them numbered with thy saints in glory everlasting
O Lord save thy people
and bless thine heritage.
Govern them and lift them up for ever.
Day by day we magnify thee;
and worship thy name, ever world without end.
Vouchsafe, O Lord to keep us this day without sin.
O Lord, have mercy upon us, have mercy upon us.
O Lord, let thy mercy lighten upon us, as our trust is in thee.
O Lord in thee have I trusted let me not be confounded.

Here's the Stanford Te Deum in C, sung by the Westminster Abbey Choir:



And at that point, we can't leave out W.A. Mozart's Te Deum in C, either, can we?