Tafsir of Ad-Dhariyat 51:18

That is, despite their little sleep and frequent night vigils, they persist in seeking forgiveness during the hours before dawn, as if they had committed crimes throughout their night and had not dedicated it to worship. Placing the verb after the pronoun (i.e., hum yastaghfirun) conveys that they are the most deserving to be described with seeking forgiveness, as if they are uniquely characterized by it due to their continuity and diligence in it.

The verse contains an implicit indication of their profound fear and their lack of arrogance regarding their acts of worship, which is evident. Interpreting "seeking forgiveness" according to its literal, well-known meaning is the most apparent interpretation, and this is what Al-Hasan held. Ibn Jarir and others recorded from him that he said: "They prayed, and when the hour of dawn arrived, they sought forgiveness."

It has been said that what is meant is their seeking of forgiveness through prayer, and upon this is what Ibn al-Mundhir and a group recorded from Ibn Umar (may Allah be pleased with them both), that he said: "They seek forgiveness" means they pray. Ibn Marduwayh also recorded this from him in a marfu' (attributed to the Prophet) form, though I do not consider it authentic. He also recorded from Anas that the Messenger of Allah (may Allah bless him and grant him peace) said: "The latter part of the night in night vigil is more beloved to me than the first part, because Allah the Almighty says: 'And in the hours before dawn, they seek forgiveness.'" It is possible that it bears this interpretation, and the apparent [meaning]—