(2) بَابُ قَوْلِ اللَّهِ تَعَالَى: {يَأْتُوكَ رِجَالاً وَعَلَى كُلِّ ضَامِرٍ يَأْتِينَ مِنْ كُلِّ فَجٍّ عَمِيقٍ لِيَشْهَدُوا مَنَافِعَ لَهُمْ}
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.
Reference: Sahih al-Bukhari 1514
In-book reference: Book 25, Hadith 2
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 26, Hadith 590