Who said "Athenians beating Spartans? Sure. In a painting."?

The Spartans (8th–4th century BC). Source: Plutarch, Sayings of Spartans, Anonymous 9 (232f).

What is the original Greek?

Λάκων ὑποτυχών ἐν τῷ πίνακι εἶπε. Translated from the original Greek by Spartan Surfers.

Athenians beating Spartans? Sure. In a painting.

The Spartans, Plutarch, Sayings of Spartans, Anonymous 9 (232f)

The source

"Athenians beating Spartans? Sure. In a painting." The Spartans said it in Plutarch, Sayings of Spartans, Anonymous 9 (232f). Translated from the original Greek by Spartan Surfers.

"Λάκων ὑποτυχών ἐν τῷ πίνακι εἶπε."

Original Greek, Plutarch, Sayings of Spartans, Anonymous 9 (232f). Greek: Bernardakis 1889 (Teubner) via Perseus.

Who said it

The Spartans (8th–4th century BC). Laconic sayings from Lycurgus, Leonidas, Dienekes and the mothers of Sparta, recorded by Herodotus and Plutarch.

Questions

Who said "Athenians beating Spartans? Sure. In a painting."?: The Spartans (8th–4th century BC). Source: Plutarch, Sayings of Spartans, Anonymous 9 (232f).
What is the original Greek?: Λάκων ὑποτυχών ἐν τῷ πίνακι εἶπε. Translated from the original Greek by Spartan Surfers.