Charles Ellicott Commentary 1 Samuel 11:9

"And they said unto the messengers that came, Thus shall ye say unto the men of Jabesh-gilead, To-morrow, by the time the sun is hot, ye shall have deliverance. And the messengers came and told the men of Jabesh; and they were glad." — 1 Samuel 11:9 (ASV)

Tomorrow, by that time the sun be hot. —That is, about noon the army of rescue will be at hand. The distance from Bezek to Jabesh was not much over twenty miles.