A certain spirit attaches itself to the human voice. A voice may be passionate or cold, whining or demanding, timid or confident, coaxing or commanding. This is not merely a matter of sounds but also a matter of attitudes or personal characteristics that become tangibly present in the voice.
The voice of God speaking in our souls also bears a characteristic spirit. It is a spirit of exalted peacefulness and confidence, of joy, of sweet reasonableness and of goodwill. It is, in short, the spirit of Jesus, and by that phrase I refer to the overall tone and internal dynamics of his personal life as a whole. (Notice Jesus’ characteristic postresurrection greeting, “Peace be with you!” John 20:19, 21, 26.)
Those who had seen Jesus had truly seen the Father, who shared the same Spirit. This Spirit marks the voice of God in our hearts. Any word that bears an opposite spirit most surely is not the voice of God.
Willard, Dallas. Hearing God Through the Year