Once someone told me that "drink of the spring" sounded like 100 years ago and "drink from the spring" was better. The clause "drink of the spring" came from my dictionary but I found something seems to be the origin of it:
“He who neglects to drink of the spring of experience is likely to die of thirst in the desert of ignorance.”― Li Bai (a Chinese poet who lived 701-762AD)
I don't know when this was translated but I can see the need for making it old-fashioned.
How about "say of"? I saw it in a translation by a native, the original is from a mid-19th century writing:
People can say of me what they will. But the fact remains that no one knows what makes me tick like I do. -- Ryuichi Sakamoto, translated by Roger Pulvers
I also found "say of" used in Bible and in the American anthem, but is "say of" old-fashioned?
=addition= Thanks for your help.:) I see that Oxford Learner's Dictionary has 'to say nothing of something' and 'no …/nothing to speak of' as idiom, so I got an impression that they are used only in negative form, but I also found 'speak of something' as idiom and I know 'Speaking of ~" is commonly used. So when it comes to 'say of' I assume it's not a matter of old-fashioned or up-to-date but it's a matter of preference or popularity..(?) oh, and it must be the matter of rhythm for an anthem.