The night prayer could be prayed as a naafilah meaning an additional deed that a person could perform irregularly.
وَهُوَ الَّذِي جَعَلَ اللَّيْلَ وَالنَّهَارَ خِلْفَةً لِّمَنْ أَرَادَ أَن يَذَّكَّرَ أَوْ أَرَادَ شُكُوراً
‘And He it is Who has put the night and the day in succession (Khilfatan), for such who desires to remember or desires to show his gratitude.’ [25:62]
However, what is more encouraged is for him to make it an act which is consistent even if it may be upon a small amount of rak’ahs.
A’isha reported Allah’s Messenger (ﷺ) as saying:
أَحَبُّ الأَعْمَالِ إِلَى اللَّهِ تَعَالَى أَدْوَمُهَا وَإِنْ قَلَّ
“The acts most pleasing to Allah are those which are done continuously, even if they are small.”
Reported by al-Bukhaari and Muslim.
Al-Imam an-Nawawi rahimahullah titled the chapter that this hadith is mentioned in with the following title: “Chapter: The virtue of a deed that is done persistently, whether it be Qiyam al-Lail or anything else.”
AbdulFattaah Bin Uthman