page 26 q1chemical bonding module and how is there no hybridization in nh3

According to the Drago’s rule, In heavier elements, the bonding occurs due to pure p-orbital and the s-electron remain in its pure form.
So in, PH3 the lone-pair remain in the s-orbitalwhile in case of NH3, the lone-pair is in sp3 orbital and since this hybridised orbital is directional so it is more basic as compared to the lone-pair present in spherically symmetricals- orbital in case of PH3.
It happens when the surrounding(here H atom)atom is of electronegativity around 2.5