It was announced this morning that Salah had extended his deal beyond the end of this season. Reports suggest the contract runs for a two-year period.
For his media conference to preview Sunday's clash with West Ham at Anfield, Slot began: "I am happy, of course. He has shown for so many years in a row how much value he has to the club, like all the fans and the team-mates they are very happy he has extended for two more years.
"Relief? For the fans I think so. It's no surprise to you I knew a bit better how the contract situation went. I knew a bit longer things were heading in the right direction. It is a big compliment to (sports director) Richard Hughes because Mo Salah, as a free agent, can go to any club he wants to."
Slot praise for Liverpool negotiators
Asked to expand on what Salah's commitment means to the club and the team, Slot was effusive.
He continued: "First of all, he has always been judged as a player, but I also see him as a human being and he is humble, works hard and puts so much effort in to become the player he is. He keeps that effort every single day. He can score goals if he is not in the best half hour or 15 mins and that is why he is mentally so strong. He has to be strong mentally and apart from the other things that is probably what stands out for me.
"How much input did I have? I am part of the process but I don't deserve the compliments, it's Mo, his agent and then FSG, Richard, they all put the effort, which means money! But also effort. What it might tell you is that it is not only a good season now we want more next season and Mo is convinced we can do so. So that is positive for us.
"A boost? I would prefer not to forget what has happened before, we're 11 clear! In the most difficult league in 10 years given who is still in Europe, so please let our fans and platers not forget how fantastic we have done so far. We lost to PSG in one of the best games I've ever beena a part of, so I want us to remember what we did. We can look back at 8 or 9 months of very good football. On average, individual performances and the team have been so good."
Meanwhile, Slot was also asked about the situation around skipper Virgil van Dijk. Like Salah before this morning's actions, Van Dijk's deal runs to the end of June.
Slot said: "You know the answer! The boring one as always. We talk about contracts if they are signed, so we talk about Mo. I am very happ with Virgil this season he has been incredible for us. Maybe some moments lately where he can do better but the other 89 mins, such an important player. Hopefully he can do the same and be our leader again.
"Hint on Sunday...I don't read all the things."
On player contracts in general, Slot concedes it has been something that has dominated the season, with Trent Alexander-Arnold another senior player who's future remains undecided.
He said, "In general people see me as relaxed and that has all to do wth the trust I have in the quality of the players and the quiality of leadership in FSG, Michael Edwards and Richard Hughes, that is why I am indeed calm, they will do what is best for the club. If that is extending then it is, if not they will find a solution. There's a reason for me to be calm. I have also spoken to Mo and followed the process. It gave me confidence.
"Sort them before the end of the season would be useful! But you know my answer, we will see what happens. You will get your answer. First of all, it is about us being happy we've seen Mo extend."
Looking ahead to West Ham
Meanwhile, Liverpool will face West Ham on the back of defeat at Fulham a week ago. Asked to reflect on the result and performance, Slot insists he was calm in the aftermath.
"I think after the game it felt to me we 'only' made three mistakes, maybe four with Ibou and it cost us three goals. I already felt it wasn't a bad performance in the first half. Three mistakes and everyone says it is the worst half of the season, football is all about being judged on goals you score and concede. The mentality at 3-1, creating chance, showed our character. I liked the second half much more, more dynamic, took risks in the right places and that led to a much better half than first. That is where we try to learn."
Slot also insists he has no issue with Ibrahima Konate after hooking him during defeat at Craven Cottage. The Dutchman says the decision was made to boost his attack and had nothing to do with the France defender's performance.
He added, "For me, if I take Konate out for a centre-back, that tells you I am not happy with his game or his injured. If I bring an attacker or midfielder, it just says we need to take more risks. Ibou improved on the ball, not that he has bad, he was France international who played World Cup final! He has improved build up. To take him off, it was for a sure for a player who can score easier than Ibou can. Taking him off at Fulham has nothing to do with where he is at. It was about taking more risks to score and we created quite a lot."
Before signing off, Slot had another final word for the big news of the day, admitting he can imagine the Reds support celebrating today over the news.
He concluded: "Like I just said it's important, I am 100% sure the fans love to see him extending, positive vibes, always good. On the other hand, Mo performed so well with you guys only talking about contracts but it is only a positive.
"If you want to sign players or keep players, it is always a positive one of our star players has made the choice to extend. It also shows how ambitous this club is, Mo, the owners and the ones who came last summer, we are ambitious to keep performing to the level this club has been at in the last few years."