What are two devices of repetition in "The Song of Slaves in the Desert" by John Greenleaf Whittier?

In "The Song of Slaves in the Desert," John Greenleaf
Whittier describes a group of slaves traveling through the desert.  As they trudge
across the sand, they sing and pray their God,
Rubee.

Whittier uses several different forms of repetition,
perhaps in an attempt to reproduce the rhythmic pulse of the slaves'
song.

One form of repetition is called
anaphora; this is the repetition of the same word or phrase at the
beginning of successive phrases or verses.  Some examples in this poem
are:

a) "Lord of peoples,
lord of lands";

b) "We
were like the leaves and sand, / We were
many."

c) "We are
weak...

We are
blind...

We are
fools."

Another type of repetition is
a refrain, a phrase that is repeated at regular intervals
throughout the poem.  The refrain of this poem is "Where are we going, Rubee?"  After it
is introduced in the poem's second line, it is repeated every 8th line of the
poem.