The Prophet (Sallallahu Alaihi Wasallam) said:"Whoever draws near to Allah during it (Ramadan) with a single characteristic
from the characteristics of (voluntary) goodness, he is like whoever
performs an obligatory act in other times. And whoever
performs an obligatory act during it, he is like whoever
performed seventy obligatory acts in other times.”
(Sahih Ibn Khuzaymah, no. 1887)