Sabrina asks, "Spurgeon's devotional says, 'Canst thou not remember the hill Mizar?' Is this a real place?"
Yes, is is a real place. David mentioned it in Psalm 42:6 when he said:
My soul is cast down within me; therefore I remember you from the land of Jordan and of Hermon, from Mount Mizar.
David seems to be indicating that Mount Mizar was one of the many places where he met with God. God encouraged him and helped him.
Now, in his time of discouragement, David is finding hope in remembering back to the times when God met with him, encouraged him, and proved His faithfulness.
Spurgeon is likely encouraging his readers to remember God’s past faithfulness when faced with current trial or difficulty. He is calling you to think back to all of the ways God has proven Himself faithful, and find encouragement in that.