What did each messenger who brought Job news of disaster say at the end of his report?

Answer: "I alone have escaped to tell you!"

All four messengers in Job 1:14-19 ended with "I alone have escaped to tell you!" (KJV: "I only am escaped alone to tell thee").

“the Sabeans swooped down and took them away. They put the servants to the sword, and I alone have escaped to tell you!””— Job 1:15 (BSB)