America! America!
God mend thine ev’ry flaw,
Confirm thy soul in self-control,
Thy liberty in law.

Katharine Lee Bates (1859-1929) American writer and poet

Poem (1893), “America,” st. 2 (1904 ed.)
    (Source)

This text was introduced in Bates' 1904 version of the song. It was not in the original version published in The Congregationalist, Vol. 80, No. 27 (1895-07-04); the end of stanza 2 originally ended:

America! America!
God shed his grace on thee
Till paths be wrought through wilds of thought
By pilgrim foot and knee!

For more information on the history of this poem and song, see America the Beautiful - Wikipedia.