Charles H. Spurgeon on Psalms 139:8

Hell in some places in Scripture signifies the lower parts of the earth, without relation to punishment: If I ascend up into heaven, thou art there; if I make my bed in hell, behold, thou art there. By "heaven" he means the upper region of the world, without any respect to the state of blessedness; and "hell" is the most opposite and remote in distance, without respect to misery. As if he had said, Let me go whither I will, thy presence finds me out. —Joseph Caryl.