It was narrated from 'Abdullah bin 'Umar that the Prophet used to say:
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).