the excellence, of night's Nafl Salat, is like excellence of Sadaqah given secretly over Sadaqah given openly
Abu Hurairah Radiyallahu 'anhu narrates that Rasullullah Sallallahu 'alaihi wasallam said: The best month for fasting, after the month of Ramadan, is Allah's month of Al-Muhar ram; and the best Salat, after obligatory Salat, is Tahajjud Salat.