سنن النسائي

It was narrated that Ibn Shihab said: "Salim told me that his father said: "I heard the Messenger of Allah (ﷺ) say the Talbiyah: "Labbaika Allahumma Labbaik, Labbaika La sharika laka Labbaik. Innal-hamda wan-ni'mata laka wal-mulk, la sharika lak (Here I am, O Allah, here I am. Here I am, You have no partner, here I am. Verily all praise and blessings are Yours, and all sovereignty, You have no partner)." 'Abdullah bin 'Umar used to say: "The Messenger of Allah (ﷺ) used to pray two Rak'ahs in Dhul-Hulaifah, then when his she-camel stood up straight with him at the Masjid of Dhul-Hulaifah, he would enter Ihram saying these words."