What is Spondet Peritiam Artis?

Legal Definition
He promises the skill of his art; he engages to do the work in a skillful or workmanlike manner. 2 Kent, Comm. 588. Applied to the engagements of workmen for hire. Story, Ballm. § 428.
-- Black's Law Dictionary
Legal Definition
He promises the skill of his art.
-- Ballentine's Law Dictionary