HOW TO START PRAYING THE VOLUNTARY NIGHT PRAYER H 1202 "Whosoever gets up for the night prayer should start it with two short units of prayers." R 1202 Muslim with a chain up to Abu Hurairah who related that the Messenger of Allah, praise and peace be upon him, said this.
1179- وعن أَبي هريرة رضي الله عنه : أنَّ النبيَّ صلى الله عليه وآله وسلم ، قَالَ : "إِذَا قَامَ أحَدُكُمْ مِنَ اللَّيْلِ فَلْيَفْتَتِحِ الصَّلاَةَ بركْعَتَيْنِ خَفِيفَتَيْنِ" رواه مسلم .