Musnad Ahmad 31:745

Ya'qub narrated to us, my father narrated to us, from Ibn Ishaq, Aban ibn Salih narrated to us, from Qasim, the freed slave of 'Amarah, from Qaza'ah, from Abu Sa'id al-Khudri, who said: I heard the Messenger of Allah, may Allah bless him and grant him peace, saying: "Do not undertake a journey except to three mosques: the Sacred Mosque (al-Masjid al-Haram), the Furthest Mosque (al-Masjid al-Aqsa), and this mosque of mine."