De Bruyne will leave Manchester City at the end of the season, though his next club is yet to be decided.
Speaking to Sky Sports, Salah said of his former Chelsea teammate: “I want to tell him congratulations for your career.
“He’s done a phenomenal job at City, and he was great for the league. I really wish him the best…and we have a space for him!”
Salah also commented on Liverpool's decision to hand him a new contract, in contrast to De Bruyne being allowed by City to leave.
He continued: "The philosophy of the club, I know how they deal with their players over 30 in the past. I didn't expect I was going to stay. It's not something bad. We see how they deal with this situation in the past.
"It took six months for the negotiations to go really quick and from January things are getting better and better. It took us a while. I think the club was testing me to see if I could still provide or not!"