Musnad Ahmad 1150:2

Qutaybah ibn Sa'id narrated to us, Ibn Lahi'ah narrated to us, from al-Rabi' ibn Sabrah, I heard 'Amr ibn Murrah al-Juhani saying: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "Whoever is here from Ma'ad, let him stand." So I stood, and he said: "Sit." He did that three times, and each time I would stand, he would say: "Sit." When it was the third time, I said: "From whom are we, O Messenger of Allah?" He said: "You are a group of Quda'ah from Himyar." 'Amr said: I kept this hadith hidden for twenty years.