Charles H. Spurgeon on Psalms 30:6

In my prosperity. (ywlvg) The word denotes peace and tranquillity, arising from an affluent prosperous condition. When God had settled him quietly on the throne, he thought all his troubles were over, and that he should enjoy uninterrupted happiness; and that God"had made his mountain so strong, as that it should never be moved; "i.e., placed him as secure from all danger as though he had taken refuge upon an inaccessible mountain; or made his prosperity firm, and subject to no more alteration, than a mountain is liable to be removed out of its place; or, raised him to an eminent degree of honour and prosperity; a mountain, by its height, being a very natural representation of a very superior condition, remarkable for power, affluence, and dignity. He had taken the fortress of Mount Sion, which was properly his mountain, as he had fixed on it for his dwelling. It was strong by nature, and rendered almost impregnable by the fortifications he had added to it. This he regarded as the effect of God's favour to him, and promised himself that his peace and happiness for the future should be as undisturbed and unshaken as Mount Sion itself. Samuel Chandler.