Musnad Ahmad 30:1502

Hassan narrated to us, Ibn Lahi'ah narrated to us, 'Ayyash bin 'Abbas al-Qatabani narrated to us, from Abu Tamim al-Zuhri, from Abu Hurairah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "When the prayer is called (iqamah), there is no prayer except the one for which the iqamah was called."