Joachim Jeremias gave an earthy description of "grace" in one of his
biblical exposes.  He responded to a student's question by saying
"Grace is like the pleasant surprise experienced by Zaccheus high in
the tree when Jesus called up to him  "Come down, I am going to dine
at your house today." The story of Zaccheus is found in Luke's gospel
chapter 19:1-10.  What is the written source of this description.  I
need it for a bibliography.

Zacchaeus was a tax collector , and a Jew. They were hated by the
general population because they were regarded as lackeys of the
Romans. The bible also mentions that he was a "small in size". Also,
many in the "job" of collecting tax, overcharged for their own
benefit. People were at a loss to know why Jesus chose this one to
spend time with. Zacchaeus was, by trying to see Jesus, showing he had
faith in Jesus, otherwise he would have stayed home and not bothered.
Jesus had the frame of mind clearly set out in Luke 15;7 " I tell you
that thus there will be more joy in heaven over one sinner that
repents, than over ninety nine righteous ones who have no need of
repentance".
The name Zacchaeus means clean,pure. He was a chief tax collector at
Jericho. Following Jesus` stay, Zacchaeus showed a changed attitude
and declared he would pay back fourfold what he had gained unjustly 
and would give half of his belongings to the poor. Jesus then
acknowledged that he was in line for salvation. Luke 19;11-28.