His saying: "By the fig and the olive." The interpretation of Qatadah is: The fig is the mountain of Damascus, and the olive is the mountain of Jerusalem.
قَوْله: ﴿والتين وَالزَّيْتُون﴾ تَفْسِيرُ قَتَادَةَ: التِّينُ: جَبَلُ دِمَشْقَ، وَالزَّيْتُون: جبل بَيت الْمُقَدّس