Is the meaning of "whoever spends the night in a state of purity" in the noble Hadith that a Muslim should be in a state of Wudu, or is it sufficient to be pure without Wudu?

There is encouragement to be in a state of purity before sleeping. It is narrated that whoever goes to bed in a state of purity, an angel stays with him in his garment, seeking forgiveness for him. This purity includes ablution (wudu), bodily cleanliness from impurities, and also inner purity through repentance from sins.