Al Allaamah Ahmad an Najmee (rahimahullah):

O slave of Allaah, may Allaah have mercy upon you; Observe the fasting of the month of Ramadhaan and standing in its night prayer. Take benefit from this opportunity, it may be that you will not get it again, as perhaps death may snatch you before the next Ramadhaan reaches you again.

Source: Istiqbaal Shahri Ramadhan:pg 28