The following obligations cannot be specifically enforced: 1. An obligation to render personal service; 2. An obligation to employ another in personal service; 3. An agreement to perform an act which the party has not power lawfully to perform when required to do so; 4. An agreement to procure the act or consent of the wife of the contracting party, or of any other third person; or, 5. An agreement, the terms of which are not sufficiently certain to make the precise act which is to be done clearly ascertainable.
