Musnad Ahmad 27:1652

'Affan narrated to us, Muhammad ibn al-Harith al-Harithi narrated to us, Muhammad ibn 'Abd al-Rahman al-Baylamani narrated to me, from his father, from 'Abdullah ibn 'Umar, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "If you meet a pilgrim, greet him, shake his hand, and ask him to seek forgiveness for you before he enters his house, for he is forgiven."