Комментарий к Тегилим 108:3

I shall awaken the dawn It is the custom of other kings that the dawn awakens them, but I awaken the dawn, for I rise at midnight, when the psaltery and the harp awaken me, as our Rabbis said (Ber. 3b): A harp was suspended above David’s bed. As soon as midnight arrived, the north wind would blow on it and it would play by itself.