The former Borussia Mönchengladbach defender joined Saints last week.
“He told me a lot of positive things," Vestergaard revealed. “He had some ups and downs here in his first season, but he was always treated well.
“The main thing he said is that he was seen as a human, not a machine or just a football player.
“I think that's very important, and the way to get the best performances out of other players.
“That was an important part of me choosing to come here."