A Dictionary of Music and Musicians/Benedicite
BENEDICITE, or the 'Song of the Three Children,' is the canticle which is used in the Anglican service after the first lesson in the morning, alternatively with the Te Deum, at the option of the minister. It is taken from the Greek continuation of Daniel, chap. iii., and is of very ancient use in the Church service, being mentioned in St. Benedict's 'Regula,' and by Amalarius as used at matins. It was also prescribed by Athanasius. The ancient Spanish and Gallican churches appointed it to come between the lessons, and in the ancient English offices it was one of several psalms with which Lauds began. It was retained by Cranmer in his 'English Liturgy' of 1549, and appointed to be used instead of the Te Deum in Lent; but this injunction was afterwards removed, and it became optional to use it at any time of the year.
In 'the Book of Common Prayer noted' which was published in 1550, the chant given for it by Marbeck is the same as that in the Sarum Breviary, but simplified, in accordance with Cranmer's wish that 'the note that shall be made thereunto, would not be full of notes, but as near as may be for every syllable a note, so that it may be sung distinctly and devoutly.'
This canticle is more fitted for a chant than any other musical form, because the second half of each verse is the same throughout. Purcell set it in his double service in B flat, but garbled the words by making the burden 'Praise him,' etc. only recur occasionally.