(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. (IT)
Reference (IT): Sahih al-Bukhari 1514 (IT)
In-book reference (IT): Book 25, Hadith 2 (IT)
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 26, Hadith 590 (IT)