This Psalmist, perhaps was a pilgrim to Jerusalem. He saw the mighty fortress of Zion, and heard his companions express confidence in its mighty defenses. But he trusted in God as the source of his help rather than in man - made citadels and nature's rocky mountains.
A Psalm of David - A Song of degrees
I will lift up mine eyes unto the hills, from whence cometh my help. My help cometh from the LORD, which made heaven and earth.
He will not suffer thy foot to be moved: he that keepeth thee will not slumber. Behold, he that keepeth Israel shall neither slumber nor sleep.
The LORD is thy keeper: the LORD is thy shade upon thy right hand. The sun shall not smite thee by day, nor the moon by night.
The LORD shall preserve thee from all evil: he shall preserve thy soul. The LORD shall preserve thy going out and thy coming in from this time forth, and even for evermore. (KJV)
A Psalm of David - A Song of degrees
He will not suffer thy foot to be moved: he that keepeth thee will not slumber. Behold, he that keepeth Israel shall neither slumber nor sleep.
The LORD is thy keeper: the LORD is thy shade upon thy right hand. The sun shall not smite thee by day, nor the moon by night.
The LORD shall preserve thee from all evil: he shall preserve thy soul. The LORD shall preserve thy going out and thy coming in from this time forth, and even for evermore. (KJV)