Hazrat Ibn Umar R.A. report that Rasulullah Sal’am said: “When you meet a Hajji (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.”
Another Hadith explains the same point. Rasulullah Sal’am is reported to have said: “The Mujaahid (fighter in the way of Allah) and the Hajji are members of Allah’s deputation. Whatever the beseech of Allah, is granted to them and whatever they beg of Him, they receive.”
In another Hadith it is mentioned that Rasulullah Sal’am once prayed “O Allah, forgive the sins of the Hajjis and forgive the sins of him for whom the Hajji prays.” It is reported that Rasulullah Sal’am made this duaa three times which emphasizes its importance. It is also reported that Hazrat Umar R.A. said: “The Hajji has the pardon of Allah and until the twentieth of Rabi ul Awwal Allah answers his prayers in which he begs forgiveness for anyone.” For these reasons it has always been the custom and habit of the learned predecessors to welcome the pilgrims, to walk with them and to ask them to pray on behalf.