German: Matthias hat zwar am Telefon was von einer Überraschung gesagt, ...
English: Matthias did mention a surprise on the telephone, ...
I'm struggling with the grammatical structure "sagen was von ..." meaning " to mention". On the one hand, this does not appear to me to be a free translation, but rather a standard grammatical construction in German for saying "to mention". On the other hand, I'm unable to find online additional examples with a similar construction.
As the verb "erwähnen" also means "to mention", I'm interested in knowing whether the following two German sentences are identical in meaning. If not, I would appreciate a translation/explanation that illustrates the difference between two.
1 - Matthias hat zwar am Telefon was von einer Überraschung gesagt.
2 - Matthias hat zwar am Telefon eine Überraschung erwähnt.
Thanking you in advance for your clarification.