PSALM 122 Jerusalem

The angel of God is mentioned in Psalm 34:7  ESV
The angel of the LORD encamps around those who fear him,
and delivers them.

In Psalm 35:4-8 is a prayer that  the angel of God
will not only defend the people of God,
but drive away and persue persons and forces which
threaten the life and honour  of God's people.

So, when in psalm 122, the word of God tells us to pray
for the peace of Jerusalem, we are praying, not only for the
peace of unity, but the peace of security.

Psalm 122:6-7 ESV
Pray for the peace of Jerusalem.
May they be secure who love you !
Peace be within your walls
and security within your towers.

In the KJV Psalm 122 verse 6 is first a command
and second a prophecy.
Pray for the peace of Jerusalem:
they shall prosper that love thee.

This is the word of God. It is addressed to all who hear or
read or sing it.  To pray for the peace of Jerusalem is to
align ourselves with the will of God.