‘In peace will I both lay me down, and sleep,
For you YHWH alone make me dwell in safety.'
David finishes with his declaration of full confidence in YHWH. The final battle is not yet over, but as he prepares for it he can afford to lie down, and yes, he even sleeps (compare Psalms 3:5). For he knows that his safety and security are in YHWH's hands. Because he is YHWH's he is confident of his safety and security in YHWH's hands. We too may sleep in peace if we are His.
The great emphasis on the sin of rebelling against YHWH's anointed finds even greater significance in the light of the coming of Jesus. Here was YHWH's Anointed par excellence. And so the psalm becomes a call to all men to lay down their arms and submit to Him.