I would let it rest wrapped in foil and then towels in a cooler. Something happens that allows the juices to concentrate in that piece of beef. Then put it in the refrigerator. To warm it, I would leave it in the foil, put in a baking dish with a high side and fill it with one inch of water. Set the oven on 175 to 200 degrees and let it come to temperature and run for 45 minutes to an hour. Then remove. The meat should be in temperature for eating it should still retain its moisture, if you cooked it right.
If you have ever been to an old time deli where they had corned beef and pastrami, they always kept the meat in a light steamer before they sliced it for sandwiches. Corned beef and pastrami is brisket. You have to go back 60 years to see that process. I do not know if they do that anymore anywhere, today except for New York City.
I have had good luck doing that without having a dry result.
Happy fourth,
Ed