'A lip' in general signifies doctrine.

In Isaiah 6:3, 7, this signifies the interior parts of a person and thus internal worship where adoration is grounded.

In Isaiah 37:29, this signifies the thought of the understanding

In Malachi 2:6, 7, this denotes doctrine grounded in charity.

(Verweise: Arcana Coelestia 1284, Arcana Coelestia 1288)

Title: The Stengthening of the Prophets

Topic: Salvation

Summary: Part of the process of becoming a prophet is to experience in a deep way one's own utter weakness, sinfulness, and ill-suitedness to the call. Then the Lord gives a new strength and something to say.

Use the reference links below to follow along in the Bible as you watch.

References:
Exodus 3:1-end
Exodus 4:1, 10, 12, 16; 6:12
Joshua 10:20
Isaiah 6:1, 5-6, 8
Ezekiel 1:26; 2:1, 6; 3:7, 9, 14
Daniel 10:1, 4-10, 16, 18
Jonah 1:1
Luke 5:1, 8
Acts of the Apostles 9:1, 5-6, 19
Revelation 1:10, 12, 17