Shakespeare has—
“When arm in arm they both came swiftly running,
Like to a pair of loving turtle-doves.”
Henry VI. Part I. Act ii. Sc. 2.
And elsewhere—
“So turtles pair that never mean to part.”
Winter’s Tale, Act iv. Sc. 3.
Again—
“As true as steel, as plantage to the moon,
As sun to day, as turtle to her mate.”