The TE Deum is an ancient hymn. It is unique in that it is a permanent part of the Divine Office. It is said(sung) at the end of Matins/Vigils/Office of Readings after the final reading and before the closing prayer on Sundays and Holy Days
You are God: we praise you;
You are the Lord: we acclaim you;
You are the eternal Father:
All creation worships you.
To you all angels, all the powers of heaven,
Cherubim and Seraphim, sing in endless praise:
Holy, holy, holy Lord, God of power and might,
Heaven and earth are full of your glory.
The glorious company of apostles praise you.
The noble fellowship of prophets praise you.
The white-robed army of martyrs praise you.