Sayyiduna Anas (may Allah be pleased with him) says: A man came to the Prophet (peace and blessings be upon him) and said: O Messenger of Allah, I commit sins. The Prophet (peace and blessings be upon him) said: "When you commit a sin, seek forgiveness from your Lord." He said: I seek His forgiveness and then commit a sin again. The Prophet (peace and blessings be upon him) said: "When you commit a sin, seek forgiveness from your Lord again." He said: I seek forgiveness and then commit a sin again. The Prophet (peace and blessings be upon him) said: "When you commit a sin again, then seek forgiveness from your Lord again." This exchange took place a fourth time, and the Prophet (peace and blessings be upon him) said: "When you commit a sin, seek forgiveness from your Lord (that is, keep doing so always), so that it is Satan who ends up the loser."
Al-Bazzar recorded it; its chain contains Bashshar bin al-Hakam al-Dabbi, whom more than one scholar declared da'if (weak), while Ibn Adi said: I hope there is no harm in him. The rest of its narrators have been declared trustworthy.
Allamah al-Haythami says: I say: More hadiths about seeking forgiveness will come after this.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب التوبة / 17532