Based On Qur'an
"And anyone who has done evil and persecute her, then he ask forgiveness of Allah, he found Allah is Forgiving, Merciful." (Qur'an, An-Nisa '4: 110)"And Allah was not to punish them while you were among them. And not (also) Allah will punish them while they seek forgiveness. "(QS. Al-Anfal 8:33)
"And (he said)," O my people, ask forgiveness of your Lord and then repent to Him, He Menu-unloaded heavy rain upon you, and He will Adds Strength to strength, and do not be turned away by sinning. "(QS. Hud 11:52)
"And your Lord Speaking," Pray to Me, will undoubtedly grant your pray. Those who boast of worship Me will enter Hell in a state of abject. "(QS. Al Mu'min 40:60)
"Celebrate the praises of thy Lord and ask His forgiveness. He is the oft. "(QS. An Nasr 110: 3)
Based On hadis
Prophet. once said: "He has opened the door for him to pray means it has been opened for him the doors of mercy. No one loved request over the request afiat / safety. Benediction is useful from what has been revealed or which have not been revealed. There is no denying al-Qadha (provision) Allah besides someone dihaturkan prayer to God. Therefore, pray diligently. "(HR. Tirmidhi)
Prophet. once said: "No Muslim can on earth who pray to Allah; it is granted by Him. Disaster or removed from him by supplication, for prayer is not for the crime or break the strap. "(HR. Tirmidhi)
"Let someone among you pray asking God what you need even asked strap sandals off." (HR. Tirmidhi)
"Who are reluctant to pray to God, God did not like him."
"Ask Allah of His Kurnia, verily, God is pleased when prompted. Seutama-primary and worship is waiting for the release of a disaster. "(HR. Tirmidhi)
The Prophet once said: "There was a believer who prayed for his fellow believers without being noticed by his brother, but angels will say: I hope you also get like him!"
"Repent to your Lord (Allah) verily, I repent to my Lord Most Holy and Most High in the day as much as one hundred times." (HR. Muslim).
Prophet. once said: Verily, a slave if done wrong, then it is written black spots dihatinya. If he was sorry and begged for forgiveness, then immediate abolition. But if he is more and more mistakes are made, it is increasingly also black spots, enough to cover the entire heart. (HR. Tirmidhi)