“It was to do with my washbag,” Slater laughs, remembering the moment the club’s legendary manager gave him a code to live by. “He told me not to go around carrying it and I knew exactly what he meant. But I’m not that kind of person. I keep it in the boot of my car.”
Within moments of our meeting in the foyer of a city centre hotel, listening to Slater speak about both the past and the future, a couple of things quickly become apparent. Casually dressed in hoodie and jeans, neither of which are emblazoned with designer labels, the 22-year-old midfielder has no interest in standing out above the crowd or desire to be noticed.
And as he traces his journey through the game, detailing the loan spells, promotions and of course his senior debut, you get the sense this is someone in love with football itself. Not obsessed with being a footballer.
“It’s always been the case,” Slater says. “My first word was ‘goal’. Seriously, it was. In school, out of school, whatever, that’s all I ever wanted to do.”
Slater is in a deep and meaningful relationship with United too, which started long before he made his debut, aged 17, during an EFL Trophy tie at Grimsby Town.
Born into a family of die-hard Blades - “My sister Isabel, she probably watches even more games than me and of course she’s got a season ticket” - he was taken to Bramall Lane by his father as a toddler although mum Michelle was the first person he told after discovering he was set for a senior call-up.
“Everyone was so proud, myself included. Because United isn’t just any club. It’s our club.”
Five years after that match at Blundell Park, where he became the youngest player ever to score for them in a first team fixture, Slater’s career is approaching a crossroads. His contract expires at the end of the season and, having helped Hull City win promotion from League One last term, is unlikely to be short of admirers should United fail to open talks about an extension.
Rattling-off his personal highlights since entering their youth programme, including that tackle on Bersant Celina - which former manager Wilder described as his “personal highlight” of the match following an FA Cup win over Ipswich - Slater’s preference is clearly to remain in South Yorkshire.
But should he be forced to depart, four seasons after “cementing” the Kosovan at Portman Road, Slater has an impressive CV to fall back on. Not to mention, having overcome adversity during all of his various loan spells, a proven track record of courage and commitment.
“I’ve always been ready to fight,” admits Slater, recounting how he was forced to win over the doubters at both Carlisle and Scunthorpe before repeating the trick at the MKM Stadium. “I didn’t start in the side at any of them and yes, when all you want to do is play, it can be tough.
"When I’m on the pitch or training, everything else is forgotten. But when you’re going home or driving home, of course you think about it.
“I did it at Brunton Park, and got myself into the eleven there. The same at Glanford Park and in Hull. The feeling there, when we knew we’d gone up, it was brilliant. What an experience. That taught me a lot about performing under pressure as well, because you know one slip and it could be over.”
“Some people reckoned it was the same when I put in that tackle on Celina,” he continues. “If I’d have got it wrong, then I might have gone according to them. But I just saw the ball and I knew I could get it. To be fair, I heard Bersant saying he liked what I’d done afterwards and I know the gaffer did as well, because of what he called it - a cementing.
"When I got back to the dressing room, Mark Duffy who was still with us at the time just looked at me and smiled:: ‘F*****g hell, Reags.’ Then he gave me a pat on the shoulder and just burst out laughing. But, like I said, I’ve always been a fighter.”
Although it would be wrong to characterise Slater as a scrapper - Grant McCann, who took him to East Yorkshire, also praised his technique and efficiency in possession - that tenacious streak could hold the key to earning a chance at United under Paul Heckingbottom; appointed as Slavisa Jokanovic’s successor following what the board described as a “strategic” review which emphasises the importance of nurturing home grown talent.
One appeared to be in the offing when the Serb, who spent only 22 games in charge before sacked last month, assessed the options at his disposal over the summer. An untimely injury meant that never materialised. But now Slater, who worked under Heckingbottom when he was under-23’s coach, is looking to force his way into the reckoning.
“I’ve had lots of really good experiences, different ones, so that’s good to have in the locker. Keep my head down, train well, give everything and make sure I’m ready to take it if it arrives - that’s what I’m planning to do.
“All I ‘ve ever wanted is to play. I’ve put 100 percent in and more wherever I’ve been. But there’s no denying it, the defeats hurt more and the wins mean more. Because it’s United.”