(2) بَابُ قَوْلِ اللَّهِ تَعَالَى: {يَأْتُوكَ رِجَالاً وَعَلَى كُلِّ ضَامِرٍ يَأْتِينَ مِنْ كُلِّ فَجٍّ عَمِيقٍ لِيَشْهَدُوا مَنَافِعَ لَهُمْ}
Narrated Jabir bin `Abdullah:
that Allah's Messenger (ﷺ) started saying, "Labbaik" from Dhul-Hulaifa when his Mount stood upright carrying him .
Reference: Sahih al-Bukhari 1515
In-book reference: Book 25, Hadith 3
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 26, Hadith 591