Sajda-e-Sahw

Forgetting to make sajda-e-sahw

Q: In Saheeh Muslim there is a hadeeth in the chapter of forgetting in salaah. The hadeeth mentions that after the salaah wherein Rasool (Sallallahu Alayhi Wasallam) performed three rakaats in salaatul Asr, Rasool (Sallallahu Alayhi Wasallam) entered his home and came back out and spoke etc. and then just made sajda sahw.

  1. People now say that if one begins to talk after the salaah wherein sajda sahw supposed to take place, he has to repeat the entire salaah. Please explain.
  2. The hadeeth mentions that Rasool (Sallallahu Alayhi Wasallam) came out angrily. Why did he become angry?