Charles Ellicott Commentary 2 Samuel 15:1

"And it came to pass after this, that Absalom prepared him a chariot and horses, and fifty men to run before him." — 2 Samuel 15:1 (ASV)

Prepared him chariots and horses. — As a preparation for his rebellion, it was necessary to impress the people with his wealth and splendor. (Compare to 1 Kings 1:5, where Adonijah does the same thing.) This was the first use in Israel of chariots and horses as a part of regal pomp.