The aim of this paper is to analyze Num 6:27 by focusing on the meaning of the verb 'samu' in context. First the 'concrete' interpretation, putting a kind of amulet on the body of the blessed person will be rejected. It is suggested to see here the double way of transmission of tradition: orally - 'say', and written - 'put my name'. That is to say that the priestly blessing included two stages: first the priest blessed, and then he wrote down the Lord's Name on the (hand or forehead), of the blessed. The Name of God on the body as an apotropaic device is already known from Cain (Gen 4:16) 'And the Lord put a mark on Cain', where in Hebrew there is the same root 'vaYasem'.
The second part of the paper deals with one of the commandments: (Exo 20:7; Deut 5:11) 'You shall not take the name of the Lord your God in vain'. It is argued that the traditional view of this commandment as denoting a false oath has no basis. However, the root 'tissa' as 'bearing' the names of the tribes (and the Name of God), is known from the High Priest (Exo 28:9 ff). From the first part of the study together with this custom and late Rabbinic interpretations, it is assumed that the third commandment intended to prevent those people who bear the Name of God from misbehaving (which might become a Hilul HaShem).