It is not authentic.

It is narrated that Abdullah Ibn Zubair (radhiallahu anhu) saw a man raising his hands and making dua before completing his salah. When the person had completed his salah, Hazrat Abdullah Ibn Zubair (radhiallahu anhu) went up to him and said: “Verily, Rasulullah (sallallahu alaihi wasallam) used to only raise his hands and make dua after completing his salah”(Majmauz Zawaaid, vol. 1, pg. 169). Is the above mentioned narration authentic? If yes, then doesn’t it justify the practice of raising hands after salaah to make duaa?