"Always your first thoughts are with the person," Slot said.
"We are all in this job so we know that it can happen, but if it happens - especially because I know him a little bit and I know how much work he puts into it - to get this news for him is a pity.
"We also know - especially us from Holland - how well he did at Ajax and he won two trophies over here, so we will see him in the near future again at a big club."