Gandalf gains entrance to Edoras.
Théoden commands him to go: ‘ Take any horse, only be gone ere tomorrow is old!’
Ganalf journeyed to Edoras to borrow a horse from the land of Rohan, here the horses were the strongest and fastest of any breeds in the world. Gandalf had one goal on his mind, to get to Frodo as fast as he could.
At this point of time Théoden was being influenced by Saruman but he wasn’t fully under the wizard’s “spell.” Théoden figured Gandalf would be far more trouble than he was actually worth, so in an effort to spare himself difficulties, he sent Gandalf away. Théoden had no idea what horse Gandalf was going to take he just wanted this wizard gone. His words, however, gave Gandalf free reign to seek out the greatest horse in Rohan. We won’t meet this horse today but he’s coming soon.
Thank you for your time and remember, the old that is strong does not wither.
– The Wandering One