Reward for performing four rakaats sunnat before Zuhr salaah

Yes, this is correct. The Hadith appears in At-Targheeb wat Tarheeb.

It is reported from Hazrat Baraa bin Aazib (radhiyallahu anhu) that Rasulullah (sallallahu alaihi wasallam) said, “The one who performs the four rakaats sunnat-e-muakkadah before zuhr receives the reward as though he performed four rakaats of tahajjud, and the one who performs four rakaats after Esha salaah receives the reward of performing four rakaats on the night of Qadar.”

And Allah Ta'ala knows best.