Adam Clarke on Ecclesiastes 6:12

For who knoweth what is good for man in this life - Those things which we deem good are often evil. And those which we think evil are often good. So ignorant are we, that we run the greatest hazard in making a choice. It is better to leave ourselves and our concerns in the hands of the Lord, than to keep them in our own.

For who can tell a man what shall be after him - Futurity is with God. While he lives, man wishes to know what is before him. When he is about to die, he wishes to know what will be after him. All this is vanity; God, because he is merciful, will reveal neither.