From my understanding he used to always pray in increments of 2 Rakaat whenever he offered any Nafl or Sunnah Salaat. Please correct me if I am wrong.
Nabi (Sallallahu alaihi wasallam) would perform nafl salah at times in increments of two rakaat, sometimes 4 rakaat, sometimes six and sometimes eight.
The ahadith showing them are present in most books of hadith. We will give a reference for each:
4 Rakaat: Sahih Bukhari (No.3376)
6 Rakaat and 8 : Sharhu Ma’anil Aathaar of Tahawi Vol.1 Pg.364(Ilmiyyah), Sunanul Kubra of Nasai (No.1414),
and Allah Ta’ala Knows Best
Ml. Husain Kadodia
STUDENT: Darul Ifta
CHECKED & APPROVED: Mufti Ebrahim Desai