In Book X (10) of The Illiad Hector (edition: Britannica Great Books of the Western World (The Illiad and The Odessey together), rendered into English prose by Samuel Butler) swears the following oath
"May Jove the thundering husband of Juno bear witnes that no other Trojan but yourself shall mount those steeds, and that you shall have your will with them for ever."
He swears this to Dolon, son of Eumedes, who agrees to, in return for Peleus's chaiot and steeds when and if they should be captured, spy on the Achaeans and try discover their plans of battle for the next day.
The oath is followed by the following sentence:
The oath he swore was bootless, but it made Dolon more keen on going.
Why is the oath bootless? Is it because Jove only has to witness (instead of may jove take my children, juno give me no sons etc).
It can't be because the oath gives him no 'booty' (treasure/loot) because the horses are the boot...
Edit: There seems to be no reason (at this point) to think Hector would go back on his word, and the horses do exist, so presuming the Trojons win (which they are at this point in the story [the Achaeans are in retreat]) there is every reason to presume that Dolon will at some point recieve the horses.
Is the oath 'bootless/useless' because the promised reward is not certain, i.e. it cannot immediately be bestowed on him?
If so why is Dolon more eager to go?