Narrated Ibn `Umar
I saw that Allah's Messenger (ﷺ) used to ride on his Mount at Dhul Hulaifa and used to start saying, "Labbaik" when the Mount stood upright.
Narrated Jabir bin `Abdullah
that Allah's Messenger (ﷺ) started saying, "Labbaik" from Dhul-Hulaifa when his Mount stood upright carrying him.