Sayyiduna Abu Basrah (may Allah be pleased with him) said: the Messenger of Allah (peace and blessings be upon him) said: "Saddles are not to be fastened except for three mosques: al-Masjid al-Haram, the Mosque of the Messenger, and al-Masjid al-Aqsa."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 2147