The evangelist John carefully notes that Jesus “wrote with His finger” on the ground a second time.The literary allusions implied by this act are masterfully chosen. First, the law of Moses was written “by the finger of God” (Exod 31:18). The tablets of the law kept in the first temple were actually produced the second time God had written the ten commandments (Exod 34:1). The second writing of the law became necessary because the first tablets had been destroyed by Moses after the mocking adultery of Israel (Exod32:6). By writing with His finger the second time, Jesus recalls the adulterous disobedience of the people of God, officiated over by Aaron, the high priest of Israel. Second, the finger of God’s hand had written judgment against the Babylon of Belshazzar, who was illegitimately using the vessels taken by Nebuchadnezzar from the first temple to dress the table of his concubines (Dan 5:1-5). By writing with His finger on the ground of the second temple, Jesus is announcing that the religious leaders have been weighed by God and found wanting. While they are presently usurping the vessels of the temple of God, they will shortly have their kingdom divided and given to the Gentiles (cf. Dan 5:24-28). The second temple, then, is a place of adultery and idolatry. Jerusalem is under divine judgment, and, like Babylon, will be destroyed.
-Warren Gage, St. John’s Vision of the Heavenly City, 71n.