Mention of the virtue of seeking forgiveness

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "Whoever seeks forgiveness abundantly, Allah Almighty makes for him relief from every worry and a way out of every hardship, and provides for him from where he does not even imagine."
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.

It is narrated from Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever commits a sin in this world and is punished for it (in the form of a prescribed penalty or the like), Allah is far too just to repeat the punishment upon His servant. And whoever commits a sin in this world and Allah conceals it for him, Allah is far too generous to call to account something He has already pardoned."
Here ends the Book of Repentance and Turning to Allah; now the Book of Manners begins.