my notary public stamp

From answerbag.com:

"The phrase "speak of the devil" is a shortened form of the medieval phrase
"speak of the devil and he shall come." It was thought that if you talked
about the devil it would attract his attention. That is why when you are
talking about someone and they show up you say speak of the devil."

Well now y'all know and knowing is half the battle. Actually - I'm a
little disappointed by this answer of "Where did 'speak of the devil' come
from?" I thought it would be this ancient lure of satanic corruption where
Lucifer had worked out a deal with Jacob the disciple. Whereas Lucifer
would give him riches in terms of unlimited bottles of wine and sheep skin
for the knowledge of Christ almighty's source of power. Then while
drinking tea with Luke and Peter, Jacob told them his story of running into
a black caped man calling himself Lucifer. As he uttered those words, the
subject showed up in person. "You scare me as the devil, good sir!" Jacob
said. And without resistance - Lucifer did a Wonder Woman type spin to
turn into THE DEVIL! Now becoming completely red and growing horns, he
caught a pitchfork that grew and shot out from the ground. Luke and Peter
luckily had bottles of Holy Water on them and began to throw. "CURSES!"
Lucifer said and ran away.

Hence, in my own demonic, corrupted, imaginery mind - this is where the
phrase "speak of the devil" came from.