Musnad Ahmad 1237:7

Ya'qub narrated to us, he said: My father narrated to us, from Ibn Ishaq, he said: Yazid ibn Abi Habib narrated to me, from Marthad ibn Abdullah al-Yazani, from Abu Basrah al-Ghifari, he said: I met Abu Hurairah while he was traveling to the Mosque of At-Tur to pray in it. He said: So I said to him: Had I reached you before you set out, you would not have set out. He said: So he said: And why? He said: So I said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "Do not set out on a journey except to three mosques: the Sacred Mosque, the Al-Aqsa Mosque, and this mosque of mine."