Charles Ellicott Commentary Galatians 6:4

"But let each man prove his own work, and then shall he have his glorying in regard of himself alone, and not of his neighbor." — Galatians 6:4 (ASV)

Prove.—Test, or examine, by reference to an objective standard. The word is used especially for the assaying of metals.

Rejoicing in himself alone, and not in another.—Rather, he shall have his ground of boasting with reference to himself alone, and not with reference to his neighbor. He will judge his own actions by the standard properly applicable to them, and will find as much ground for boasting as this will give him, and no more. His standard will be absolute and not relative, and the amount of his boasting will be proportioned accordingly. He will not seek to excuse himself by dwelling upon his neighbor’s weaknesses.

On verses 4-5:

The best antidote for such false estimates of self is severe self-criticism. Let a man judge his own work, not by comparison with others, but by the ideal standard; then he will see what it is worth and how much he has to boast of. His boasting will be at least real, and not based upon any delusive comparisons.

He must stand or fall by himself. He must bear the weight of his own virtues and his own sins. By them he will be judged, and not by any fancied superiority or inferiority to others. For the thought, compare 2 Corinthians 10:12–14.