﴿ قَالَ رَبِّ إِنِّى دَعَوْتُ قَوْمِى لَيْلًۭا وَنَهَارًۭا ﴾

“[And after a time, Noah] said: "O my Sustainer! Verily, I have been calling unto my people night and day”

When he despaired of them, after calling them to faith for 950 years, and they refused to believe or heed his advice, (He said: My Lord! Lo! I have called unto my people) to repent and believe in Allah's divine Oneness (night and day) at night and during the day.