Allah tells us how He responded to His servant and Messenger Nuh, peace be upon him, when he prayed to Him against his people for their disbelief in him:

(Then he invoked his Lord (saying): "I have been overcome, so help (me)!") (54:10)

(And Nuh said: "My Lord! Leave not any inhabitant of the disbelievers on the earth! If You leave them, they will mislead Your servants, and they will beget none but wicked disbelievers) (71:26-27). So Allah says here,

(And (remember) Nuh, when he cried (to Us) aforetime. We answered to his invocation and saved him and his family) meaning, those who believed with him, as Allah says elsewhere:

(...and your family – except him against whom the Word has already gone forth – and those who believe. And none believed with him, except a few) [11: 40].

(from the great distress.) meaning, from difficulty, rejection and harm. For he remained among them for one thousand years less fifty, calling them to Allah, and no one had believed in him except for a few. His people were plotting against him and advising one another century after century, generation after generation, to oppose him.

(We helped him against the people) means, 'We saved him and helped him against the people,'

(who denied Our Ayat. Verily, they were a people given to evil. So We drowned them all.) meaning, Allah drowned them all, and not one of them was left on the face of the earth, as their Prophet had prayed would happen to them.