Duas of a Haaji

Regarding the dua's of the Haaji, the following appears in the books of Hadith

Hadhrat Ibn Umar (Radhiyallahu Anhuma) reports that Rasulullah (Sallallahu Alaihi Wasallam) said: "When you meet a haaji (on
his way home) then greet him, shake hands with him and ask him to beg forgiveness of Allah on your behalf before he enters his home, for his prayer for forgiveness is accepted since he is forgiven by Allah for his sins." (Musnad Ahmed)

In another Hadith it is mentioned that Rasulullah (Sallallahu Alaihi Wasallam) once made dua: "O Allah, forgive the sins of the haajis and forgive the sins of the one for whom the haaji makes dua." It is reported that Rasulullah (Sallallahu Alaihi Wasallam) made this dua three times.

It is also reported that Hadhrat Umar (Radhiyallahu Anhu) had said: "The Haaji receives the forgiveness of Allah Ta'ala until the tenth of Rabi ul Awwal and Allah Ta'ala accepts his dua's for those on behalf of whom he begs forgiveness."

And Allah Ta'ala (الله تعالى) knows best.

Fazaail-e-Hajj Pg. 22