After searching Minas Tirith's archives Gandalf must return to the Shire -- and Denethor would say goodbye.
Gandalf walked around the old horse, examining her. Running his hand down one leg, he sighed as he felt the bump on her knee. So you have been ridden hard.
Taking a carrot from his pocket, he held it out invitingly. Her lips caressed Gandalf's palm; soon the carrot was devoured.
She is a poor beast indeed. But still... He saw that some fire still burned in her eyes. Her spirit thrived, if her body faltered. And he was not one to look a gift horse in the mouth.
Turning, he nodded at Denethor. "Thank you. 'Tis an unexpected gift, but welcome all the same."