An old-fashioned way to sing through the alphabet, pairing letters with a promise to play nicely together. A few letters get skipped for the sake of the rhyme, so don't expect a full A to Z.
From Mother Goose / Nursery Rhymes (traditional). See the whole collection.
A, B, C, and D,
Pray, playmates, agree.
E, F, and G,
Well, so it shall be.
J, K, and L,
In peace we will dwell.
M, N, and O,
To play let us go.
P, Q, R, and S,
Love may we possess.
W, X, and Y,
Will not quarrel or die.
Z, and ampersand,
Go to school at command.
Public domain. Text from The Real Mother Goose (Blanche Fisher Wright, 1916), via Project Gutenberg. View the source edition