Correct Way of Shaving Pubic Hair

Assalaamualaikum , we have seen some hadiths on the importance of shaving pubic hair , but what is the right way of doing it? Is it ok if it is cut short with scissors? **Narrated By Abu Huraira : I heard the Prophet saying. "Five practices are characteristics of the Fitra: circumcision, shaving the pubic hair, cutting the moustaches short, clipping the nails, and depilating the hair of the armpits." Sahih al-Bukhari, The Book of Dress, Hadith Number:5952** I've asked some friends though , and they say use blade. But blades seem a bit harsh . Similarly there is a ruling of shaving it off within 40 days. So I wanted to know the truth behind this "40 day" term . Please answer with a hadith. So my question is , would scissors be alright to cut short with, and is there a 40 day threshold after which all good deeds are nulled? Baarakallahu feekum.