Bukayr bin al-Akhnas narrates from his father: I recited this verse at night: "And it is He who accepts repentance from His servants, pardons misdeeds, and knows what you do." [Surah al-Shura: 25]
He says: I was in doubt and did not know whether it was "yaf'alun" (they do) or "taf'alun" (you do). In the morning I went to Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him), intending to ask him, but while I was sitting (with him) a man asked about a man who first commits zina with a woman and then marries her. Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) recited this verse to him: "And it is He who accepts repentance from His servants, pardons misdeeds, and knows what you do." [Surah al-Shura: 25]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13886