In the context of this beautiful verse, the "man" is none other than the Lord Jesus Christ. To one who had been traveling in the heat of the desert, such as the Sinai wilderness, nothing was so welcome as the cool shadows behind a great rock in which one could rest for a while from the hardships of the wearying land. The symbol of the shadow is often used in the Old Testament to illustrate the refreshing presence of the Lord.
"He that dwelleth in the secret place of the most High shall abide under the shadow of the Almighty" (Psalm 91:1). Wherever His loved ones go, He is there, and our dwelling place is there in His shadow.
There is safety there, also. "Because thou hast been my help, therefore in the shadow of thy wings will I rejoice" (63:7). "He shall cover thee with his feathers, and under his wings shalt thou trust" (91:4). He is the great Eagle as well as the great Rock, and finally also the great Tree. "As the apple tree among the trees of the wood, so is my beloved among the sons. I sat down under his shadow with great delight, and his fruit was sweet to my taste" (Song of Solomon 2:3).
The shadow of a great rock in a weary land, the shadow of the wings of a great eagle, the shadow of a delightful fruit tree, all of these speak beautifully of the refreshing, protecting, satisfying shadow of His presence. These are the shadows of the Almighty God, who made heaven and earth, and now holds us in His hand. "I have covered thee in the shadow of mine hand, that I may plant the heavens, and lay the foundations of the earth, and say unto Zion, Thou art my people" (Isaiah 51:16). HMM