One of the secrets of the universe is repentance which is the key to many problems of the human being. In Ayahs 9 to 12 of Surah Nuh, this point has been described clearly:

“Further I (Nuh/Noah (AS)) have spoken to them in public and secretly in private, saying: Ask forgiveness from your Lord; as God is Oft-Forgiving; God will send rain to you in abundance; give you increase in wealth and sons/children, and bestow on you gardens and rivers (of flowing waters).”

In these Ayahs, it has been revealed that the very important secret of existence is the same repentance which consequently is followed by Divine Forgiveness, Divine Blessings including plenty of rain, Divine Help by granting wealth, children, gardens and rivers. By looking at the Quranic teachings it becomes clear that Allah (SWT) granted a favour to the human being by designating repentance for them. That is why all the prophets used to repent to God and were required to do so as mentioned in Ayah 41 of Surah Ibrahim, Ayah 28 of Surah Nuh, Ayah 55 of Surah Qafir, and Ayah 19 of Surah Muhammad (PBUH).

Source: en.shafaqna.com