A cat may looke on a King.

John Heywood (1497?-1580?) English playwright and epigrammist

Proverbs, Part 2, ch. 5 (1546)
    (Source)

Revised spelling from the 1874 edition. Original editions had it, "A cat maie looke on a kyng." This is the earliest text found with this recorded as an English proverb.

Thomas Fuller included the phrase ("A Cat may look upon a King") in his Gnomologia, # 35 (1732).

For more information on this phrase and its history, see: meaning and origin of the phrase ‘a cat may look at a king’ – word histories.