Therefore my people shall know my name: therefore [they shall know] in that day that I [am] he that doth speak: behold, [it is] I.
Ver. 6. Therefore my people shall know my name,] sc., That I am Jehovah; as Exo 6:3 the God of Amen, Isa 65:16 who "will not suffer my faithfulness to fail, nor alter the thing that is gone out of my mouth." Psa 89:33-34 And it shall therefore be so because my name - that nomen maiestativum - hath been blasphemed and vilified. God's people fare the better for their enemies' insolencies.
That I am he that doth speak: behold, it is I.] Or, That it is I that do speak, saying, Lo, here I am. This some understand to be the second person in the Trinity, the eternal Son of the eternal Father, called "the Word," Joh 1:1 and there are those who give us this rule - Where the Old Testament bringeth in God appearing and speaking, we are to understand it always to be the second person. See John 12:37,42 .