George Leo Haydock

I am certain that he (God) is able to keep that which I have committed to him [6] against that day. That is, to the day of judgment. St. Paul here means that which he had committed, or as it were deposited in the hands of God; to wit, the treasure of an eternal reward, due in some measure to St. Paul for his apostolical labours. This treasure, promised to those that live well, the apostle hopes he has placed and deposited in the hands of God, who will reward him, and repay him at the last day. This is the common interpretation. (Witham)