(I [Noah] said [to them]: 'Ask forgiveness from your Lord; verily; He is Oft-Forgiving. He will send rain to you in abundance; and give you increase in wealth and children; and bestow on you gardens; and bestow on you rivers. (Qur'an 71: 10-12)
So seek forgiveness from Allah more often and you will reap the benefits of doing so: peace of mind, lawful provisions, righteous offspring, and plentiful rain.
(And [commanding you]: 'Seek the forgiveness of your Lord, and turn to Him in repentance, that He may grant you good enjoyment, for a term appointed. And that He may bestow His abounding Grace to every owner of grace [i.e. the one who helps and serves the needy and deserving, physically and with his wealth, and even with good words].)
(Qur'an 11: 3)
And the Prophet (Blessings and Peace be upon him) said:
"Whosoever seeks forgiveness (from Allah) often, then Allah makes for him a good ending for every matter of concern and provides for him a way out of every tight situation. "
Related in Bukhari is a hadith that is known as the chief of Al-lstighfaar (i.e., of supplications with which one asks Allah for forgiveness):
"O' Allah, You are my Lord and none has the right to be worshipped except you. You have created me and I am your slave; and I am upon your covenant and promise as much as I am able to be. I seek refuge in you from the evil that I have perpetrated. I confess to you your favor upon me, and I confess to you my sin. So forgive me; for verily, none forgives sins except you."