Right. That particular verb-form is a remnant of the subjunctive mood. Other main verbs that take a clause housed with a subjunctive verb-form are: advise, ask, beg, decide, decree, desire, dictate, insist, intend, move, order, petition, propose, recommend, request, require, resolve, suggest, urge, and vote.
2. *The man of whom the red car is parked in front of our house is a prominent physician in this house. <ungrammatical>
"the red car" belongs to the man; it's the man's car. A possessive pronoun is required: The man whose red car ...
"whom" is an object pronoun:
3. The man of whom you speak ... <'whom' refers back to 'the man'>
4. The man whom you speak of ... <'whom' refers back to 'the man'>
5. You speak of the man/whom ... <'the man'/'whom functions as an object>
Hope that helps.
Student or Learner