תהילים יח:ג פירוש: רש״י

my rock For You saved me at the Rock of the Divisions (I Sam. 23:28), when I was trapped between Saul and his men, to be caught, as it is stated (in I Sam. 23:26): “but Saul and his men were encircling to David and his men etc.”

and my fortress Heb. ומצודתי, an expression of a fortress.

my rock Heb. צורי, an expression of a rock.