Charles Ellicott Commentary Isaiah 19:13

"The princes of Zoan are become fools, the princes of Memphis are deceived; they have caused Egypt to go astray, that are the corner-stone of her tribes." — Isaiah 19:13 (ASV)

The princes of Noph. —Probably, as in the Septuagint, Noph is the same as Memphis. The name has been derived (1) from Ma-m-pthah (“the house of Pthah,” an Egyptian deity of the Hephaestus, or Vulcan type); or (2), and more correctly, from Men-nepher (“place of the good”). This also was, as in Hosea 9:6 (where we have the form Moph), one of the chief royal cities of Lower Egypt, and the seat of the Ethiopian dynasty then ruling.

Even they that are the stay of the tribes thereof. —Better, the corner-stone of the castes. The word is the same as the “corner” of Zechariah 10:4, the “chief” of Judges 20:2; 1 Samuel 14:38, and describes the position of superiority among the Egyptian castes claimed by the priest-rulers of Zoan and Noph.