Albert Barnes on Matthew 25:37-39

Then shall the righteous, etc. This answer is indicative of humility--a deep sense of their being unworthy such commendation. They will feel that their poor acts of kindness have come so far short of what they should have been, that they have no claim to praise or reward. It is not, however, to be supposed that in the day of judgment this will be actually said by the righteous, but that this would be a proper expression of their feelings.