Frank J. Wilstach, comp. A Dictionary of Similes. 1916.

Secure

Secure as the grave.
—Anonymous

Secure as in the cell of a saint.
—Samuel Foote

Secure as happy yesterdays.
—James Russell Lowell

Secure as the firmament.
—George Meredith

Secure, as evening shuts behind the day.
—T. Buchanan Read

Secure as sleep.
—William Shakespeare

Secure as the orchard-turf.
—Bayard Taylor

Secure as a mathematical demonstration.
—Lewis Theobald