30) is a cantata for four soloists, SATB choir and organ composed by Benjamin Britten in 1943 and uses text from the poem Jubilate Agno by Christopher Smart (1722–1771).

The poem, written while Smart was in an asylum, depicts idiosyncratic praise and worship of God by different things including animals, letters of the alphabet and musical instruments.

The cantata was commissioned by the Reverend Walter Hussey for the celebration of the 50th anniversary of the consecration of St Matthew's Church, Northampton.

Before writing Rejoice in the Lamb, Britten had established himself as a musical interpreter of traditional texts, as demonstrated with A Ceremony of Carols (1942) and his song cycle Les Illuminations (1939).

[1] In 1942, soon after returning to England from the United States, Britten was commissioned to write a choral piece for the 50th anniversary of the consecration of St Matthew's Church, Northampton, which took place the following year.

Britten chose to set music to this poem for his cantata, inspired by the far-reaching ways in which Smart depicted and manifested God.

[12] Whilst at its core the poem is, according to Christopher Headington, "a work expressing praise and an affirmation of faith",[13] Peter Evans writes that Smart demonstrates this in an "eccentric" manner, depicting the various forms in which God manifests himself in the world: a cat, a mouse, letters of the alphabet and musical instruments.

[14] Mark Riddles, writing in The Choral Journal, says that Smart's "bewildering text seems to ramble between insight and insanity, biblical citation and mystic emanation, deep reverence and lighthearted playfulness".

Mystic Praise V. Closing Hymn Rejoice in the Lamb has widely been recognised for its uniqueness and creativity, especially within the realm of Church music.

[40] The poet Peter Porter writes that Rejoice in the Lamb "enshrines some of the purest responses ever made by a musician to the very heart of that mystery which we know as poetry".

[43] A version of Rejoice in the Lamb for chorus, solos and orchestral accompaniment was arranged by Imogen Holst and published by Boosey & Hawkes.