Musnad Ahmad 27:436

'Abd al-Razzaq narrated to us, Dawud—meaning Ibn Qays—informed us, from Zayd ibn Aslam, who said: My father sent me to Ibn 'Umar, and I said: "May I enter?" He recognized my voice and said: "O my son, when you come to a people, say: 'Peace be upon you' (As-salamu 'alaykum). If they respond to you, then say: 'May I enter?'" He then saw his son, Waqid, dragging his lower garment, so he said: "Raise your lower garment, for I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'Whoever drags his garment out of pride, Allah will not look at him.'"