When entering Ihram at the Miqat, the jamaah haji makes the intention and says: 'Allahumma inni ureedul-Hajja fa yassirhu li wa taqabbalhu minni' (O Allah, I intend to perform Haji, so make it easy for me and accept it from me). Then the jamaah haji begins reciting the Talbiyah.
اللَّهُمَّ إِنِّي أُرِيدُ الْحَجَّ فَيَسِّرْهُ لِي وَتَقَبَّلْهُ مِنِّي، اللَّهُمَّ إِنِّي نَوَيْتُ أَدَاءَ الْعُمْرَةِ فَاجْعَلْهَا مَقْبُولَةً وَسَعْيِي مَشْكُورًا وَذَنْبِي مَغْفُورًا
Allahumma inni ureedul-Hajja fa yassirhu li wa taqabbalhu minni. Allahumma inni nawaytu ada'al-Umrati faj'alha maqbulatan wa sa'yi mashkuran wa dhanbi maghfura.
Meaning: O Allah, I intend to perform Haji, so make it easy for me and accept it from me. O Allah, I intend to perform Umrah, so make it accepted, my effort appreciated, and my sins forgiven.
Source: Sahih al-Bukhari #1546Nabi (shallallahu alaihi wa sallam) said: 'Whoever enters Ihram for Haji or Umrah from Masjid al-Aqsa to Masjidil Haram, his previous and future sins will be forgiven.' (Sunan Abu Dawud 1741)
اللَّهُمَّ إِنِّي أُرِيدُ الْحَجَّ فَيَسِّرْهُ لِي وَتَقَبَّلْهُ مِنِّي، اللَّهُمَّ إِنِّي نَوَيْتُ أَدَاءَ الْعُمْرَةِ فَاجْعَلْهَا مَقْبُولَةً وَسَعْيِي مَشْكُورًا وَذَنْبِي مَغْفُورًا
The Prophet (peace be upon him) prayed Dhuhr at Madinah with four rak'at and prayed Asr at Dhul-Hulayfah with two rak'at, then he spent the night at Dhul-Hulayfah. When he mounted his camel and it stood up with him at al-Bayda', he recited the Talbiyah.