Without the commas, the phrase is restrictive. It tells you WHICH man. With commas, the first sentence would be wrong if you are trying to convey which person is your husband.
With the commas, it's additional (or nonrestrictve) information.
The book that is on the table is for you. Which book? The one that is one the table. This is necessary information.
The book, which is on the table, is for you. This is just additional information about the book.
[a writer, not a teacher]
Student or Learner