Jayson Tatum said he was stunned when he first learned over the summer that Jaylen Brown had been traded to the Philadelphia 76ers.

"We was in Vegas. I just got done playing pickup the first day," he said on a video on his YouTube channel. "[ESPN's Shams Charania] walked over. He handed me the towel. He's like, 'Yo, put this over your face. Don't react. They just traded him.' I'm like, 'Oh s--t.' I'm like, 'Where?' He said, 'Philly.' I said, 'We traded him down the street?' So, I was just as much caught off guard as the rest of the world."

Tatum went on to speak about what his time with Brown in Boston meant to him.

"I've very much have been transparent about how thankful I personally am for our relationship and what we were able to accomplish over nine years," he said. "Talk about 2017-26. Jayson and Jaylen, like you won't ever be able to talk about one of us without the other. And you know just our ability to grow up as kids and go through our ups and downs and people talking about, one of us had to go, and we couldn't win together. And just, there's a lot of s--t that we had to deal with, and I will always say I knew every time I stepped on that court that, when it was time to go to war, I looked to my left and to my right and No. 7 was over there. I knew that he was going to do whatever it took for us to to win. You know the way that we pushed each other, I definitely made him better and he made me better. And we made our team better. We made this organization better. We won a championship. Like we were forever stitched in stone in NBA history. We held up that trophy. It won't ever be forgotten."

The Celtics traded Brown to the Sixers for Paul George, two first-round picks and two second-round picks over the summer. While there were rumblings that a trade could go down, sending Brown to a rival came as a pretty huge surprise.

Even to Tatum.