Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Allah, the Lord of Might, stretches out His Hand at night so that the one who sinned during the day may repent, and stretches out His Hand during the day so that the one who sinned at night may repent, until the sun rises from the west."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20766