Midrash su Salmi 87:1

“Of the sons of Korah, a song with musical accompaniment, whose foundation is on the mountains of the Sanctuary. The Lord loves the gates of Zion more than all the dwellings of Jacob.” (Psalms 87:1-2) Raba said to Rafrem bar Pappa: let the master tell us some of the precious words you said to us in the synagogue in the name of R’ Chisdah. He replied: This is what R’ Chisdah said ‘what does the verse “The Lord loves the gates of Zion more than all the dwellings of Jacob” mean? It means that God loves the gates distinguished by the way of Jewish law (halacha) more than the synagogues and the study halls. This is what R’ Chiya bar Aba said in the name of Ulah: from the day on which the Holy Temple was destroyed the Holy One has nothing in the world except for the four cubits of the law... Another explanation of “whose foundation is on the mountains of the Sanctuary.” (Tehillim 87:1) The foundation of Jerusalem is in the merit of two sacred mountains – Mount Sinai and Mount Moriah.