Psalm 54; key verse, verse 4—It is the Lord who sustains my life.
David asks for the Lord’s help when abandoned and betrayed.
This psalm is titled To the Chief Musician. With stringed instruments. A Contemplation of David when the Ziphites went and said to Saul, “Is David not hiding with us?” There were actually two times when the Ziphites betrayed David unto King Saul, first in 1 Samuel 23 and the second in 1 Samuel 26. David escaped both times, but the circumstances of this psalm seem to best fit the circumstances of 1 Samuel 23, when David learned of the Ziphite betrayal but before the deliverance of God was displayed (1 Samuel 23:26-29).
This is one of the few psalms with a specific musical direction: With stringed instruments. It is also called A Contemplation. The Hebrew word for Contemplation (maskil) might be better understood as instruction.
Behold, God is my helper. Though a hunted man, David could confidently expect God’s help. His present adversity had not led him to question the goodness of God, but to appeal to it. It is the Lord who sustains my life. The sense of this remarkable statement is that the LORD is among those who help me by upholding my life.
The Psalmist finds his life is threatened, as were Jesus’ and Jeremiah’s, and he finds God as his helper who rescues him from death. In our opposition God does not forsake those who trust in Him.
Collect for Psalm 54: Father, hear our prayer and come to the aid of your Church. Mercifully deliver us from evil, so that from the rising of the sun to its setting we may offer you a pure sacrifice of praise; through your Son, Jesus Christ our Lord.  -14 September 2021
 The Crucifixion, Schnorr Von Carolsfeld woodcuts © WELS permission granted for personal and congregational use
 Collect for Psalm 54, For All the Saints, A Prayer Book For and By the Church, Vol. IV © 1996 The American Lutheran Publicity Bureau, Delhi, NY