Which is as a bridegroom coming out of his chamber - That is, when he rises in the morning. He rises from the darkness of the night, and comes forth as the bridegroom comes out of the chamber where he has slept. The allusion is to the bright, and joyful, and cheerful aspect of the rising sun. The image of the bridegroom is employed because we associate with a bridegroom the idea of hilarity, cheerfulness, joy. The essential image is that the sun seems to rise from a night of repose, as man does in the morning, and that after such a night of repose he goes forth with cheerfulness and alacrity to the employments of the day. The figure is an obvious but a very beautiful one, though there is a transition from the image employed in the previous verse, where the sun is represented as dwelling in a tent or tabernacle fitted up for it in the heavens. In the next member of the sentence the figure is again changed, by his being represented as a man prepared to run a race.
And rejoiceth as a strong man to run a race - As a man who is vigorous and powerful, when he enters on a race. He is girded for it; he summons all his strength; he seems to exult in the idea of putting his strength to the test, and starting off on his career. Compare the note at 1 Corinthians 9:24-27. The same comparison which is employed here occurs in the Zendavesta, ii. 106. DeWette. The idea is that the sun seems to have a long journey before him, and puts forth all his vigour, exulting in the opportunity of manifesting that vigour, and confident of triumphing in the race.