Jamieson, Fausset and Brown on Ecclesiastes 9:2

2. All things ... alike--not universally; but as to death. Ec 9:2-10 are made by Holden the objection of a skeptical sensualist. However, they may be explained as Solomon's language. He repeats the sentiment already implied in Ec 2:14; 3:20; 8:14.

one event--not eternally; but death is common to all.

good--morally.

clean--ceremonially.

sacrificeth--alike to Josiah who sacrificed to God, and to Ahab who made sacrifice to Him cease.

sweareth--rashly and falsely.