What did the soldiers say as they mockingly saluted Jesus in Mark 15?

Answer: Hail, King of the Jews!

In the Praetorium the soldiers put a purple robe and a crown of thorns on Jesus and saluted, "Hail, King of the Jews!"

“Then the soldiers led Jesus away into the palace (that is, the Praetorium) and called the whole company together. They dressed Him in a purple robe, twisted together a crown of thorns, and set it on His head. And they began to salute Him: “Hail, King of the Jews!””— Mark 15:16-18 (BSB)