Mishkat al-Masabih

Ibn ‘Umar said that God’s messenger used to perform two rak’as in Dhul Hulaifa, then when the she-camel stood up with him on its back at the mosque of Dhul Hulaifa, he shouted these words, saying, “Lubbaik, O God, labbaik labbaik wa-sa‘daik ('Always ready to obey.’) ; good is in Thy hands; labbaik; desire and action are directed towards Thee. (Bukhari and Muslim, the wording being Muslim's.) (It is strange to find a tradition from Bukhari and Muslim in section (b). The author has explained in his introduction that section (a) is confined to Bukhari and Muslim and section (b) to other authorities)

وَعَنِ ابْنِ عُمَرَ قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَرْكَعُ بِذِي الْحُلَيْفَةِ رَكْعَتَيْنِ ثُمَّ إِذَا اسْتَوَتْ بِهِ النَّاقَةُ قَائِمَةً عِنْدَ مَسْجِدِ ذِي الْحُلَيْفَةِ أَهَلَّ بِهَؤُلَاءِ الْكَلِمَاتِ وَيَقُولُ: «لَبَّيْكَ اللَّهُمَّ لَبَّيْكَ لَبَّيْكَ وَسَعْدَيْكَ وَالْخَيْرُ فِي يَدَيْكَ لَبَّيْكَ وَالرَّغْبَاءُ إِلَيْكَ وَالْعَمَل» . مُتَّفق عَلَيْهِ وَلَفظه لمُسلم