When passing through a doorway with a ''mezuzah'', some Jews touch the ''mezuzah'' and kiss their fingers.
An expression of devotion to Torah. This custom originated as a result of a story brought down in the Talmud (Tractate Avodah Zarah 11a). A Roman Caesar sent guards to arrest Onkelos, the son of Kalonymus, a convert to Judaism who wrote the Biblical commentary Targum Onkelos, so that he be put to death. When the guards seized Onkelos, he explained to them the basis for faith in the Jewish God and enticed them with the benefits a life of Judaism has to offer until they could not resist their urge to convert, and they released him.
When the Caesar realized what had happened, he sent another set of guards, but this time, with explicit instructions not to listen to the man at all. When they arrived to capture him, Onkelos tried to convince them to release him, but to no avail, because they were under orders not to listen to him. As they pulled him from his house, he touched the mezuzah on the doorpost. When one of the guards asked him what it was that he touched, he replied as follows: "A king of flesh and blood sits in the palace while his servants guard from outside. Yet our Lord allows his servants to sit inside while he guards from outside." When they heard this, these guards, too, could not resist their urge and converted to Judaism.
