The law of preserving the possibility; meaning that Allah (swt) does not generalize, however, most mistakes come from generalizations, He (swt) talks about the People of the Scripture among the Jews, but this does not mean that all the Jews who were present had these characteristics, for some of them had faith, truthfulness and sincerity in their hearts, as He (swt) states in this verse.

﴿وَهُمْ يَسْجُدُونَ﴾ {and prostrating [in prayer].}: The Jews do not prostrate in their prayers, so what is meant by prostration here is the submission to Allah (swt), and there are a number of their rabbis who became Muslims truly. This is the law of preserve the possibility.

﴿آنَاء اللَّيْلِ﴾ {during periods of the night}: What is meant here is one of the hours of the night, and the night prayer is the most time when the servant is close to his Lord, at night when man is calm, and it is the time of rest so if a person specifies this time for worship, he will be in a closest state to his Lord. The Prophet (saws) told us:

“A slave becomes nearest to his lord (Allah) when he is in prostration. So increase supplications while prostrating.”[1]

So how if his prostration is during the night! However, here are many verses that mention the night prayer, such as:

وَمِنَ اللَّيْلِ فَتَهَجَّدْ بِهِ نَافِلَةً لَّكَ عَسَى أَن يَبْعَثَكَ رَبُّكَ مَقَامًا مَّحْمُودًا 

{And from [part of] the night, pray with it as additional [worship] for you; it is expected that your Lord will resurrect you to a praised station} (Al-Israa: 79)

[1] Sahih Muslim, Book of Prayer, Hadith No. 482.