Mishkat al-Masabih #3775

Ka‘b b. Malik said: When God’s Messenger intended to go on an expedition he always pretended to be going somewhere else till that expedition, meaning the one to Tabuk. God’s Messenger undertook it in extreme heat, facing a long journey, desert country and a numerous enemy. He made clear to the Muslims what they were about to do in order that they might get ready the equipment for their expedition, telling them where he was going. Bukhari transmitted it.