﴿ إِلَّا رَحْمَةًۭ مِّنَّا وَمَتَٰعًا إِلَىٰ حِينٍۢ ﴾

“unless it be by an act of mercy from Us and a grant of life for a [further span of] time.”

Unless by mercy from Us) unless by a blessing from Us that will save them from drowning (and as comfort for a while) until the time of their death and destruction.